SEC Form N-CSR filed by Eaton Vance Tax-Managed Buy-Write Income Fund Eaton Vance Tax-

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Item 1. Reports to Stockholders

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Eaton Vance

Tax-Managed Buy-Write Income Fund (ETB)

Annual Report

December 31, 2023

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Commodity Futures Trading Commission Registration

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The Commodity Futures Trading Commission (“CFTC”) has adopted regulations that subject registered investment companies and advisers to regulation by the CFTC if a fund invests more than a prescribed level of its assets in certain CFTC-regulated instruments (including futures, certain options and swap agreements) or markets itself as providing investment exposure to such instruments. The investment adviser has claimed an exclusion from the definition of “commodity pool operator” under the Commodity Exchange Act with respect to its management of the Fund. Accordingly, neither the Fund nor the adviser with respect to the operation of the Fund is subject to CFTC regulation. Because of its management of other strategies, the Fund’s adviser and Parametric Portfolio Associates LLC (Parametric), sub-adviser to the Fund, are registered with the CFTC as commodity pool operators. The adviser and Parametric are also registered as commodity trading advisors.

Managed Distribution Plan.

 Pursuant to an exemptive order issued by the Securities and Exchange Commission (Order), the Fund is authorized to distribute long-term capital gains to shareholders more frequently than once per year. Pursuant to the Order, the Fund’s Board of Trustees approved a Managed Distribution Plan (MDP) pursuant to which the Fund makes monthly cash distributions to common shareholders, stated in terms of a fixed amount per common share.

The Fund currently distributes monthly cash distributions equal to $0.0932 per share in accordance with the MDP. You should not draw any conclusions about the Fund’s investment performance from the amount of these distributions or from the terms of the MDP. The MDP will be subject to regular periodic review by the Fund’s Board of Trustees and the Board may amend or terminate the MDP at any time without prior notice to Fund shareholders. However, at this time there are no reasonably foreseeable circumstances that might cause the termination of the MDP.

The Fund may distribute more than its net investment income and net realized capital gains and, therefore, a distribution may include a return of capital. A return of capital distribution does not necessarily reflect the Fund’s investment performance and should not be confused with “yield” or “income.” With each distribution, the Fund will issue a notice to shareholders and a press release containing information about the amount and sources of the distribution and other related information. The amounts and sources of distributions contained in the notice and press release are only estimates and are not provided for tax purposes. The amounts and sources of the Fund’s distributions for tax purposes will be reported to shareholders on Form 1099-DIV for each calendar year.

Fund shares are not insured by the FDIC and are not deposits or other obligations of, or guaranteed by, any depository institution. Shares are subject to investment risks, including possible loss of principal invested.

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Annual Report

December 31, 2023

Eaton Vance

Tax-Managed Buy-Write Income Fund

Table of Contents
Management’s Discussion of Fund Performance	2
Performance	4
Fund Profile	5
The Fund's Investment Objectives, Principal Strategies and Principal Risks	6
Summary of Fund Expenses	11
Trading and NAV Information	12
Endnotes and Additional Disclosures	13
Financial Statements	14
Report of Independent Registered Public Accounting Firm	28
Federal Tax Information	29
Dividend Reinvestment Plan	30
Management and Organization	32
Privacy Notice	35
Important Notices	37

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Table of Contents

Eaton Vance

Tax-Managed Buy-Write Income Fund

December 31, 2023

Management’s Discussion of Fund Performance

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Economic and Market Conditions

For U.S. equity investors, the 12-month period ended December 31, 2023, was a roller-coaster ride, driven largely by shifting perceptions of whether the U.S. Federal Reserve (the Fed) could bring the world’s largest economy in for a soft landing, and changing expectations of how long interest rates might remain high.

As the period opened in January 2023, U.S. equities began a rally that lasted through July. The initial tailwind was ChatGPT, an artificial intelligence (AI) application that led investors to perceive AI might become the next big innovation to drive the information technology (IT) sector. As a result, IT -- one of the worst-performing sectors in 2022 -- became a standout sector in 2023. Earlier recession fears that had weighed on stock prices receded as more investors came to view the U.S. economy as doing surprisingly well.

But from August through October 2023, the bond market halted the stock market’s momentum. As investors feared the Fed might keep rates higher for longer than they had anticipated just a few months earlier, longer-term bond interest rates rose sharply. Given the potential for relatively attractive returns with lower risk than stocks, many investors shifted asset allocations from equities to bonds.

In the final two months of the period, however, U.S. equities made another U-turn, as investors again revised their expectations of what the Fed might do. Encouraged by cooling economic data and declining inflation, investors began to conclude the Fed was done raising interest rates -- and might begin lowering rates as early as March 2024.

In response, the U.S. stock market ended the period on a high note, with the S&P 500® Index, a broad measure of U.S. stocks; the blue-chip Dow Jones Industrial Average®; and the technology-laden Nasdaq Composite Index each rising more than 9% in November and more than 4% in December 2023. Unlike the equity rally during the first half of the period driven by a handful of large-cap technology-related stocks, the year-end rally extended across a wider range of market capitalizations, with the small-cap Russell 2000® Index keeping pace with its large-cap brethren in November, and significantly outperforming them in December.

For the period as a whole, U.S. equity performance was also strong. The S&P 500® Index returned 26.29%, the Dow Jones Industrial Average® returned 16.18%, the Nasdaq Composite Index returned 44.64%, and the Russell 2000® Index returned 16.93%.

Fund Performance

For the 12-month period ended December 31, 2023, Eaton Vance Tax-Managed Buy-Write Income Fund (the Fund) returned 18.02% at net asset value of its common shares (NAV), underperforming its equity benchmark, the S&P 500® Index (the Index), which returned 26.29%; but outperforming its options benchmark, the Cboe S&P 500 BuyWrite Index

SM

, which returned 11.82%.

The Fund’s options overlay strategy (the options strategy) -- designed to help limit the Fund’s exposure to market volatility and contribute to current income -- was the largest single detractor from Fund performance relative to the Index during the period. The options strategy may be beneficial during times of market weakness, but may also detract from performance during periods of market strength.

When the market was trending upward, as it was for much of the period, the options strategy of writing -- that is, selling -- stock index call options on the Fund’s underlying common stock portfolio hurt performance versus the Index. This occurred because market returns above short call option strikes -- in other words, the Fund’s losses on the call options it sold -- were greater than the premium income generated from selling those call options.

The Fund’s common stock portfolio underperformed the Index, detracting from Index-relative performance during the period as well. On an individual stock basis, the largest detractors from performance versus the Index were underweight positions in electric vehicle maker Tesla, Inc. (Tesla) and Meta Platforms, Inc. (Meta), the social media giant behind Facebook, Instagram, and Messenger.

To stimulate sales, Tesla announced price cuts during the period that weighed on profit margins and led the company to lower earnings projections. Despite that negative news, Tesla’s stock price doubled during the period because investors still viewed it as a leader in long-term growth opportunities involving electric cars and autonomous driving.

Meta’s stock price nearly tripled during the period, as advertising revenues rebounded on improved ad targeting, while profit margins exceeded expectations due to more rational spending on longer-term initiatives.

On a sector basis, stock selections in the consumer discretionary, health care, and industrials sectors detracted from Fund performance versus the Index during the period.

See Endnotes and Additional Disclosures in this report.

Past performance is no guarantee of future results. Returns are historical and are calculated net of management fees and other expenses by determining the percentage change in net asset value (NAV) or market price (as applicable) with all distributions reinvested in accordance with the Fund’s Dividend Reinvestment Plan. Furthermore, returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Performance at market price will differ from performance at NAV due to variations in the Fund’s market price versus NAV, which may reflect factors such as fluctuations in supply and demand for Fund shares, changes in Fund distributions, shifting market expectations for the Fund’s future returns and distribution rates, and other considerations affecting the trading prices of closed-end funds. Investment return and principal value will fluctuate so that shares, when sold, may be worth more or less than their original cost. Performance for periods less than or equal to one year is cumulative. Performance is for the stated time period only; due to market volatility, current Fund performance may be lower or higher than the quoted return. For performance as of the most recent month-end, please refer to eatonvance.com.

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Table of Contents

Eaton Vance

Tax-Managed Buy-Write Income Fund

December 31, 2023

Management’s Discussion of Fund Performance

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In contrast, the largest individual stock contributor to performance relative to the Index was an overweight position in NVIDIA Corp. The semiconductor maker’s share price more than tripled during the period, lifted by increased demand for its high-end graphics processing units in the burgeoning artificial intelligence, or AI, industry.

On a sector basis, stock selections in the energy, real estate, utilities, and information technology sectors contributed to performance versus the Index during the period.

Fund Distributions

Pursuant to an exemptive order issued by the Securities and Exchange Commission (the Order), the Fund is authorized to distribute long-term capital gains to shareholders more frequently than once per year. Pursuant to the Order, the Fund’s Board of Trustees approved a Managed Distribution Plan (MDP) pursuant to which the Fund makes monthly cash distributions to common shareholders. The Fund’s MDP had no effect on the Fund’s investment strategy during the most recent fiscal year and is not expected to have an effect in future periods, but distributions in excess of Fund returns will cause its per share NAV to erode. Investors should not draw any conclusions about the Fund’s investment performance from the amount of its distribution or from the terms of its MDP.

For the period from January 1, 2023 to December 31, 2023, the Fund made monthly distributions of $0.0932 per share. The Fund’s distributions may be comprised of amounts characterized for federal income tax purposes as qualified and non-qualified ordinary dividends, capital gains and non-dividend distributions, also known as return of capital distributions. The federal income tax character of distributions is determined after the end of the calendar year and reported to shareholders on the Internal Revenue Service’s form 1099-DIV. For additional information, see Note 2 in the Notes to Financial Statements herein.

See Endnotes and Additional Disclosures in this report.

Past performance is no guarantee of future results. Returns are historical and are calculated net of management fees and other expenses by determining the percentage change in net asset value (NAV) or market price (as applicable) with all distributions reinvested in accordance with the Fund’s Dividend Reinvestment Plan. Furthermore, returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Performance at market price will differ from performance at NAV due to variations in the Fund’s market price versus NAV, which may reflect factors such as fluctuations in supply and demand for Fund shares, changes in Fund distributions, shifting market expectations for the Fund’s future returns and distribution rates, and other considerations affecting the trading prices of closed-end funds. Investment return and principal value will fluctuate so that shares, when sold, may be worth more or less than their original cost. Performance for periods less than or equal to one year is cumulative. Performance is for the stated time period only; due to market volatility, current Fund performance may be lower or higher than the quoted return. For performance as of the most recent month-end, please refer to eatonvance.com.

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Table of Contents

Eaton Vance

Tax-Managed Buy-Write Income Fund

December 31, 2023

Performance

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Portfolio Manager(s)

Thomas C. Seto of Parametric Portfolio Associates LLC and Charles B. Gaffney and Douglas R. Rogers, CFA, CMT of Eaton Vance Management

% Average Annual Total Returns 1	Inception Date	One Year	Five Years	Ten Years
Fund at NAV	04/29/2005	18.10%	9.33%	7.36%
Fund at Market Price	—	7.47	8.29	7.33
S&P 500® Index	—	26.29%	15.68%	12.03%
Cboe S&P 500 BuyWrite Index SM	—	11.82	6.08	5.57

% Premium/Discount to NAV 2
As of period end	(8.66)%

Distributions 3
Total Distributions per share for the period	$1.118
Distribution Rate at NAV	7.87%
Distribution Rate at Market Price	8.62

Growth of $10,000

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This graph shows the change in value of a hypothetical investment of $10,000 in the Fund for the period indicated. For comparison, the same investment is shown in the indicated index.

See Endnotes and Additional Disclosures in this report.

Past performance is no guarantee of future results. Returns are historical and are calculated net of management fees and other expenses by determining the percentage change in net asset value (NAV) or market price (as applicable) with all distributions reinvested in accordance with the Fund’s Dividend Reinvestment Plan. Furthermore, returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Performance at market price will differ from performance at NAV due to variations in the Fund’s market price versus NAV, which may reflect factors such as fluctuations in supply and demand for Fund shares, changes in Fund distributions, shifting market expectations for the Fund’s future returns and distribution rates, and other considerations affecting the trading prices of closed-end funds. Investment return and principal value will fluctuate so that shares, when sold, may be worth more or less than their original cost. Performance for periods less than or equal to one year is cumulative. Performance is for the stated time period only; due to market volatility, current Fund performance may be lower or higher than the quoted return. For performance as of the most recent month-end, please refer to eatonvance.com.

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Table of Contents

Eaton Vance

Tax-Managed Buy-Write Income Fund

December 31, 2023

Fund Profile

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Sector Allocation (% of total investments) 1

Top 10 Holdings (% of total investments) 1
Apple, Inc.	7.6%
Microsoft Corp.	7.6
Amazon.com, Inc.	3.7
NVIDIA Corp.	3.6
Alphabet, Inc., Class A	2.4
Alphabet, Inc., Class C	2.0
Berkshire Hathaway, Inc., Class B	1.9
UnitedHealth Group, Inc.	1.8
JPMorgan Chase & Co.	1.8
Broadcom, Inc.	1.8
Total	34.2%

 

Footnotes:

1	Depictions do not reflect the Fund’s option positions. Excludes cash and cash equivalents.

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Table of Contents

Eaton Vance

Tax-Managed Buy-Write Income Fund

December 31, 2023

The Fund's Investment Objectives, Principal Strategies and Principal Risks

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Investment Objectives.

The Fund’s primary investment objective is to provide current income and gains, with a secondary objective of capital appreciation. In pursuing its investment objectives, the Fund will evaluate returns on an after-tax basis, seeking to minimize and defer shareholder federal income taxes.

Principal Strategies.

The Fund’s strategy consists of owning a portfolio of common stocks and selling covered call options (a “buy-write strategy”). Under normal market conditions, the Fund’s investment program consists primarily of: (1) owning a diversified portfolio of common stocks that seeks to exceed the total return performance of the S&P 500® Composite Stock Price Index® (the “S&P 500®”); and (2) selling S&P 500® call options on a continuous basis on substantially the full value of its holdings of common stocks. Under normal market conditions, the Fund invests at least 80% of its total assets in a diversified portfolio of common stocks that seeks to exceed the total return performance of the S&P 500®.

Due to tax considerations, the Fund intends to limit the overlap between its stock portfolio holdings (and any subset thereof) and the S&P 500® to less than 70% on an ongoing basis. The Fund’s stock holdings may include stocks not included in the S&P 500®.

The Fund expects to sell index call options on a continuous basis on substantially the full value of its holdings of common stocks. Under normal conditions, at least 80% of the value of the Fund’s total assets are subject to written index call options.

The Fund invests primarily in common stocks of U.S. issuers. The Fund may invest up to 10% of its total assets in securities of foreign issuers, including American Depositary Receipts (“ADRs”), Global Depositary Receipts (“GDRs”) and European Depositary Receipts (“EDRs”). The Fund normally expects that its assets will be invested across a broad range of industries and market sectors. Stocks included in the S&P 500® generally have growth characteristics. The Fund may invest a portion of its assets in stocks of mid-capitalization companies.

In addition to writing index call options, the Fund may invest up to 20% of its total assets in other derivative investments acquired for hedging, risk management and investment purposes, provided that no more than 10% of the Fund’s total assets may be invested in such derivative instruments acquired for non-hedging purposes. To seek to protect against price declines in securities holdings with large accumulated gains, the Fund may use various hedging techniques (such as the sale of futures contracts on stocks and stock indices and options thereon, equity swaps, covered short sales and forward sales of stocks).

During unusual market conditions, the Fund may invest up to 100% of its assets in cash or cash equivalents temporarily, which may be inconsistent with its investment objectives, principal strategies and other policies.

Principal Risks

Market Discount Risk.

As with any security, the market value of the common shares may increase or decrease from the amount initially paid for the common shares. The Fund’s common shares have traded both at a premium and at a discount relative to NAV. The shares of closed-end management investment companies frequently trade at a discount from their NAV. This is a risk separate and distinct from the risk that the Fund’s NAV may decrease.

Investment and Market Risk.

An investment in common shares is subject to investment risk, including the possible loss of the entire principal amount invested. An investment in common shares represents an indirect investment in the securities owned by the Fund, which are generally traded on a securities exchange or in the over-the-counter markets. The value of these securities, like other market investments, may move up or down, sometimes rapidly and unpredictably. Because the Fund intends, under normal market conditions, to sell index call options on a continuous basis on substantially the full value of its common stock holdings, the Fund’s appreciation potential from equity market performance will be limited. The common shares at any point in time may be worth less than the original investment, even after taking into account any reinvestment of distributions.

The value of investments held by the Fund may increase or decrease in response to social, economic, political, financial, public health crises or other disruptive events (whether real, expected or perceived) in the U.S. and global markets and include events such as war, natural disasters, epidemics and pandemics, terrorism, conflicts and social unrest. These events may negatively impact broad segments of businesses and populations and may exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted. Certain securities and other investments held by the Fund may experience increased volatility, illiquidity, or other potentially adverse effects in reaction to changing market conditions. Monetary and/or fiscal actions taken by U.S. or foreign governments to stimulate or stabilize the global economy may not be effective and could lead to high market volatility. No active trading market may exist for certain investments held by the Fund, which may impair the ability of the Fund to sell or to realize the current valuation of such investments in the event of the need to liquidate such assets.

Issuer Risk.

The value of securities held by the Fund may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

Equity Securities Risk.

The value of equity securities and related instruments may decline in response to adverse changes in the economy or the economic outlook; deterioration in investor sentiment; interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer and sector-specific considerations; unexpected trading activity among retail investors; or other factors. Market conditions may affect certain types of stocks to a greater extent than other types of stocks. If the stock market declines in value, the value of the Fund’s equity securities will also likely decline. Although prices can rebound, there is no assurance that values will return to previous levels.

See Endnotes and Additional Disclosures in this report.

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Table of Contents

Eaton Vance

Tax-Managed Buy-Write Income Fund

December 31, 2023

The Fund's Investment Objectives, Principal Strategies and Principal Risks

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Option Strategy Risk.

The Fund’s option strategy seeks to take advantage of, and its effectiveness is dependent on, a general excess of option price implied volatilities for the S&P 500® over realized index volatilities. This market observation is often attributed to an excess of natural buyers over natural sellers of S&P 500® index options. There can be no assurance that this imbalance will apply in the future over specific periods or generally. It is possible that the imbalance could decrease or be eliminated by actions of investors, including the Fund, that employ strategies seeking to take advantage of the imbalance, which could have an adverse effect on the Fund’s ability to achieve its investment objective.

Risk of Selling Index Call Options.

The purchaser of an index call option has the right to any appreciation in the value of the index over the exercise price of the call option as of the valuation date of the option. Because their exercise is settled in cash, sellers of index call options such as the Fund cannot provide in advance for their potential settlement obligations by acquiring and holding the underlying securities. The Fund intends to mitigate the risks of its options activities by holding a diversified portfolio of stocks that the Fund’s investment adviser believes collectively approximate the characteristics of the indices on which options are written. The Fund will not, however, hold stocks that fully replicate the indices on which it writes call options. Due to tax considerations, the Fund intends to limit the overlap between its stock holdings (and any subset thereof) and each index on which it has outstanding options positions to less than 70% on an ongoing basis. The Fund’s stock holdings will normally include stocks not included in the indices on which it writes call options. Consequently, the Fund bears the risk that the performance of its stock portfolio will vary from the performance of the indices on which it writes call options. As the writer of index call options, the Fund will forgo, during the option’s life, the opportunity to profit from increases in the value of the applicable index above the sum of the option premium received and the exercise price of the call option, but retains the risk of loss, minus the option premium received, should the value of the applicable index decline. When a call option is exercised, the Fund will be required to deliver an amount of cash determined by the excess of the value of the applicable index at contract termination over the exercise price of the option. Thus, the exercise of index call options sold by the Fund may require the Fund to sell portfolio securities to generate cash at inopportune times or for unattractive prices.

The trading price of options may be adversely affected if the market for such options becomes less liquid or smaller. The Fund may close out a call option by buying the option instead of letting it expire or be exercised. There can be no assurance that a liquid market will exist when the Fund seeks to close out a call option position by buying the option.

Derivatives Risk.

The Fund’s exposure to derivatives involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other investments. The use of derivatives can lead to losses because of adverse movements in the price or value of the security, instrument, index, currency, commodity, economic indicator or event underlying a derivative (“reference instrument”), due to failure of a counterparty or due to tax or regulatory constraints. Derivatives may create leverage in the Fund, which represents a non-cash exposure to the underlying reference instrument. Leverage can increase both the risk and return potential of the Fund. Derivatives risk may be more significant when derivatives are used to enhance return or as a substitute for a cash investment position, rather than solely to hedge the risk of a position held by the Fund. Use of derivatives involves the exercise of specialized skill and judgment, and a transaction may be unsuccessful in whole or in part because of market behavior or unexpected events. Changes in the value of a derivative (including one used for hedging) may not correlate perfectly with the underlying reference instrument. Derivative instruments traded in over-the-counter markets may be difficult to value, may be illiquid, and may be subject to wide swings in valuation caused by changes in the value of the underlying reference instrument. If a derivative’s counterparty is unable to honor its commitments, the value of Fund shares may decline and the Fund could experience delays in (or be unable to achieve) the return of collateral or other assets held by the counterparty. The loss on derivative transactions may substantially exceed the initial investment. A derivative investment also involves the risks relating to the reference instrument underlying the investment.

Tax-Sensitive Investing Risk.

The Fund may hold a security in order to achieve more favorable tax-treatment or to sell a security in order to create tax losses. The Fund’s utilization of various tax-management techniques may be curtailed or eliminated by tax legislation, regulation or interpretations. The Fund may not be able to minimize taxable distributions to shareholders and a portion of the Fund’s distributions may be taxable.

Tax Risk.

Although the Fund seeks to minimize and defer the federal income taxes incurred by common shareholders in connection with their investment in the Fund, there can be no assurance that it will be successful in this regard. Market conditions may limit the Fund’s ability to generate tax losses or to generate income taxed at favorable tax rates. The Fund’s tax-managed strategy may cause the Fund to hold a security in order to achieve more favorable tax-treatment or to sell a security in order to create tax losses. The Fund’s ability to utilize various tax-management techniques may be curtailed or eliminated in the future by tax legislation, regulation or interpretations. Distributions paid on the common shares may be characterized variously as net investment income (taxable at ordinary income rates), qualified dividends and capital gains dividends (each taxable at long-term capital gains rates) or return of capital (not currently taxable). The ultimate tax characterization of the Fund’s distributions made in a calendar year may not finally be determined until after the end of that calendar year. Distributions to a common shareholder that are a return of capital will be tax free up to the amount of the common shareholder’s current tax basis in his or her common shares, with any distribution amounts exceeding such basis treated as capital gain on a deemed sale of common shares. Common shareholders are required to reduce their tax basis (not below zero) in common shares by the amount of tax-free return of capital distributions received, thereby increasing the amount of capital gain (or decreasing the amount of capital loss) to be recognized upon a later disposition of the common shares. In order for Fund distributions of qualified dividend income to be taxable at favorable long-term capital gains rates, the Fund must meet certain holding period and other requirements with respect to the dividend-paying stock in its portfolio, and a common shareholder must meet certain prescribed holding period and other requirements with respect to his or her common shares. If positions held by the Fund were treated as “straddles” for federal income tax purposes, dividends on such positions would not constitute qualified dividend income subject to favorable income tax treatment. Gain or loss on positions in a straddle are subject to special (and generally disadvantageous) rules.

See Endnotes and Additional Disclosures in this report.

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Eaton Vance

Tax-Managed Buy-Write Income Fund

December 31, 2023

The Fund's Investment Objectives, Principal Strategies and Principal Risks

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Foreign Investment Risk.

Foreign investments can be adversely affected by political, economic and market developments abroad, including the imposition of economic and other sanctions by the United States or another country against a particular country or countries, organizations entities and/or individuals. There may be less publicly available information about foreign issuers because they may not be subject to reporting practices, requirements or regulations comparable to those to which United States companies are subject. Adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund’s investments. Foreign markets may be smaller, less liquid and more volatile than the major markets in the United States, and as a result, Fund share values may be more volatile. Trading in foreign markets typically involves higher expense than trading in the United States. The Fund may have difficulties enforcing its legal or contractual rights in a foreign country. Depositary receipts are subject to many of the risks associated with investing directly in foreign instruments, including the political and economic risks of the underlying issuer’s country and, in the case of depositary receipts traded on foreign markets, currency risk.

Currency Risk.

Exchange rates for currencies fluctuate daily. The value of foreign investments may be affected favorably or unfavorably by changes in currency exchange rates in relation to the U.S. dollar. Currency markets generally are not as regulated as securities markets and currency transactions are subject to settlement, custodial and other operational risks.

Liquidity Risk.

The Fund is exposed to liquidity risk when trading volume, lack of a market maker or trading partner, large position size, market conditions, or legal restrictions impair its ability to sell particular investments or to sell them at advantageous market prices. Consequently, the Fund may have to accept a lower price to sell an investment or continue to hold it or keep the position open, sell other investments to raise cash or abandon an investment opportunity, any of which could have a negative effect on the Fund’s performance. These effects may be exacerbated during times of financial or political stress.

Interest Rate Risk.

The premiums from writing index call options and amounts available for distribution from the Fund’s options activity may decrease in declining interest rate environments. The value of the Fund’s common stock investments may also be influenced by changes in interest rates. Higher yielding stocks and stocks of issuers whose businesses are substantially affected by changes in interest rates may be particularly sensitive to interest rate risk.

Inflation Risk.

Inflation risk is the risk that the value of assets or income from investments will be worth less in the future as inflation decreases the value of money. As inflation increases, the real value of the common shares and distributions thereon can decline.

Dividend Capture Trading Risk.

The use of dividend capture strategies will expose the Fund to higher portfolio turnover, increased trading costs and potential for capital loss or gain, particularly in the event of significant short-term price movements of stocks subject to dividend capture trading.

Risk of Investing in Smaller and Mid-Sized Companies.

The Fund may make investments in stocks of companies whose market capitalization is considered middle sized or “mid-cap.” Smaller and mid-sized companies often are newer or less established companies than larger companies. Investments in smaller and mid-sized companies carry additional risks because earnings of these companies tend to be less predictable; they often have limited product lines, markets, distribution channels or financial resources; and the management of such companies may be dependent upon one or a few key people. The market movements of equity securities of smaller and mid-sized companies may be more abrupt or erratic than the market movements of equity securities of larger, more established companies or the stock market in general. Historically, smaller and mid-sized companies have sometimes gone through extended periods when they did not perform as well as larger companies. In addition, equity securities of smaller and mid-sized companies generally are less liquid than those of larger companies. This means that the Fund could have greater difficulty selling such securities at the time and price that the Fund would like.

Risk of “Growth” Stock Investing.

The Fund invests substantially in stocks with “growth” characteristics. Growth stocks can react differently to issuer, political, market and economic developments than the market as a whole and other types of stocks. Growth stocks tend to be more expensive relative to their earnings or assets compared to other types of stocks. As a result, growth stocks tend to be sensitive to changes in their earnings and more volatile than other types of stocks.

Leverage Risk.

Certain Fund transactions may give rise to leverage. Leverage can result from a non-cash exposure to an underlying reference instrument. Leverage can also result from borrowings or issuance of preferred shares. Leverage can increase both the risk and return potential of the Fund. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations. Leverage may cause the Fund’s NAV to be more volatile than if it had not been leveraged, as certain types of leverage may exaggerate the effect of any increase or decrease in the Fund’s portfolio securities. The loss on leveraged investments may substantially exceed the initial investment.

Risks Associated with Active Management.

The success of the Fund’s investment strategy depends on portfolio management’s successful application of analytical skills and investment judgment. Active management involves subjective decisions and there is no guarantee that such decisions will produce the desired results or expected returns.

Recent Market Conditions.

The outbreak of COVID-19 and efforts to contain its spread have resulted in closing borders, enhanced health screenings, changes to healthcare service preparation and delivery, quarantines, cancellations, disruptions to supply chains and customer activity, as well as general concern and uncertainty. The impact of this coronavirus, and the effects of other infectious illness outbreaks, epidemics or pandemics, may be short term or may continue for an extended period of time. Health crises caused by outbreaks of disease, such as the coronavirus outbreak, may exacerbate other pre-existing political, social and economic risks and disrupt normal market conditions and operations. For example, a global pandemic or other widespread

See Endnotes and Additional Disclosures in this report.

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Item 2. Code of Ethics

The registrant (sometimes referred to as the “Fund”) has adopted a code of ethics applicable to its Principal Executive Officer, Principal Financial Officer and Principal Accounting Officer. The registrant undertakes to provide a copy of such code of ethics to any person upon request, without charge, by calling 1-800-262-1122. The registrant has not amended the code of ethics as described in Form N-CSR during the period covered by this report. The registrant has not granted any waiver, including an implicit waiver, from a provision of the code of ethics as described in Form N-CSR during the period covered by this report.

Item 3. Audit Committee Financial Expert

The registrant’s Board of Trustees (the “Board”) has designated George J. Gorman and Scott E. Wennerholm, each an independent trustee, as audit committee financial experts. Mr. Gorman is a certified public accountant who is the Principal at George J. Gorman LLC (a consulting firm). Previously, Mr. Gorman served in various

capacities at Ernst & Young LLP (a registered public accounting firm), including as Senior Partner. Mr. Gorman also has experience serving as an independent trustee and audit committee financial expert of other mutual fund complexes. Mr. Wennerholm is a private investor. Previously, Mr. Wennerholm served as a Trustee at Wheelock College (postsecondary institution), as a Consultant at GF Parish Group (executive recruiting firm), Chief Operating Officer and Executive Vice President at BNY Mellon Asset Management (investment management firm), Chief Operating Officer and Chief Financial Officer at Natixis Global Asset Management (investment management firm), and Vice President at Fidelity Investments Institutional Services (investment management firm).

Item 4. Principal Accountant Fees and Services

(a) –(d)

The following table presents the aggregate fees billed to the registrant for the registrant’s fiscal years ended December 31, 2022 and December 31, 2023 by the registrant’s principal accountant, Deloitte & Touche LLP (“D&T”), for professional services rendered for the audit of the registrant’s annual financial statements and fees billed for other services rendered by D&T during such periods.

(e)(1) The registrant’s audit committee has adopted policies and procedures relating to the pre-approval of services provided by the registrant’s principal accountant (the “Pre-Approval Policies”). The Pre-Approval Policies establish a framework intended to assist the audit committee in the proper discharge of its pre-approval responsibilities. As a general matter, the Pre-Approval Policies (i) specify certain types of audit, audit-related, tax, and other services determined to be pre-approved by the audit committee; and (ii) delineate specific procedures governing the mechanics of the pre-approval process, including the approval and monitoring of audit and non-audit service fees. Unless a service is specifically pre-approved under the Pre-Approval Policies, it must be separately pre-approved by the audit committee.

The Pre-Approval Policies and the types of audit and non-audit services pre-approved therein must be reviewed and ratified by the registrant’s audit committee at least annually. The registrant’s audit committee maintains full responsibility for the appointment, compensation, and oversight of the work of the registrant’s principal accountant.

(e)(2) No services described in paragraphs (b)-(d) above were approved by the registrant’s audit committee pursuant to the “de minimis exception” set forth in Rule 2-01(c)(7)(i)(C) of Regulation S-X.

(f) Not applicable.

(g) The following table presents (i) the aggregate non-audit fees (i.e., fees for audit-related, tax, and other services) billed to the registrant by D&T for the registrant’s fiscal years ended December 31, 2022 and December 31, 2023; and (ii) the aggregate non-audit fees (i.e., fees for audit-related, tax, and other services) billed to the Eaton Vance organization by D&T for the same time periods.

(h) The registrant’s audit committee has considered whether the provision by the registrant’s principal accountant of non-audit services to the registrant’s investment adviser and any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant that were not pre-approved pursuant to Rule 2-01(c)(7)(ii) of Regulation S-X is compatible with maintaining the principal accountant’s independence.

(i) Not applicable.

(j) Not applicable.

Item 5. Audit Committee of Listed Registrants

The registrant has a separately-designated standing audit committee established in accordance with Section 3(a)(58)(A) of the Securities and Exchange Act of 1934, as amended. George J. Gorman, Keith Quinton, Scott E. Wennerholm (Chair), and Nancy A. Wiser are the members of the registrant’s audit committee.

Item 6. Schedule of Investments

Please see schedule of investments contained in the Report to Stockholders included under Item 1 of this Form N-CSR.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies

The Board of the Fund has adopted a proxy voting policy and procedure (the “Fund Policy”), pursuant to which the trustees have delegated proxy voting responsibility to the Fund’s investment adviser and adopted the investment adviser’s proxy voting policies and procedures (the “Policies”) which are described below. The trustees will review the Policies annually. In the event that a conflict of interest arises between the Fund’s shareholders and the investment adviser, the administrator, or any of their affiliates or any affiliate of the Fund, the investment adviser will generally refrain from voting the proxies related to the companies giving rise to such conflict until it consults with the Board, or any committee, sub-committee or group of independent trustees identified by the Board, which will instruct the investment adviser on the appropriate course of action. If the Board Members are unable to meet and the failure to vote a proxy would have a material adverse impact on the Fund, the investment adviser may vote such proxy, provided that it discloses the existence of the material conflict to the Chairperson of the Fund’s Board as soon as practicable and to the Board at its next meeting.

The Policies are designed to promote accountability of a company’s management to its shareholders and to align the interests of management with those shareholders. An independent proxy voting service (“Agent”), currently Institutional Shareholder Services, Inc., has been retained to assist in the voting of proxies through the provision of vote analysis, implementation and recordkeeping and disclosure services. The investment adviser will generally vote proxies through the Agent. The Agent is required to vote all proxies in accordance with customized proxy voting guidelines (the “Guidelines”) and/or refer them back to the investment adviser pursuant to the Policies.

The Agent is required to establish and maintain adequate internal controls and policies in connection with the provision of proxy voting services, including methods to reasonably ensure that its analysis and recommendations are not influenced by a conflict of interest. The Guidelines include voting guidelines for matters relating to, among other things, the election of directors, approval of independent auditors, executive compensation, corporate structure and anti-takeover defenses. The investment adviser may cause the Fund to abstain from voting from time to time where it determines that the costs associated with voting a proxy outweigh the benefits derived from exercising the right to vote or it is unable to access or access timely ballots or other proxy information, among other stated reasons. The Agent will refer Fund proxies to the investment adviser for instructions under circumstances where, among others: (1) the application of the Guidelines is unclear; (2) a particular proxy question is not covered by the Guidelines; or (3) the Guidelines require input from the investment adviser. When a proxy voting issue has been referred to the investment adviser, the analyst (or portfolio manager if applicable) covering the company subject to the proxy proposal determines the final vote (or decision not to vote) and the investment adviser’s Proxy Administrator (described below) instructs the Agent to vote accordingly for securities held by the Fund. Where more than one analyst covers a particular company and the recommendations of such analysts voting a proposal conflict, the investment adviser’s Global Proxy Group (described below) will review such recommendations and any other available information related to the proposal and determine the manner in which it should be voted, which may result in different recommendations for the Fund that may differ from other clients of the investment adviser.

The investment adviser has appointed a Proxy Administrator to assist in the coordination of the voting of client proxies (including the Fund’s) in accordance with the Guidelines and the Policies. The investment adviser and its affiliates have also established a Global Proxy Group. The Global Proxy Group develops the investment adviser’s positions on all major corporate issues, creates the Guidelines and oversees the proxy voting process. The Proxy Administrator maintains a record of all proxy questions that have been referred by the Agent, all applicable recommendations, analysis and research received and any resolution of the matter. Before instructing the Agent to vote contrary to the Guidelines or the recommendation of the Agent, the Proxy Administrator will provide the Global Proxy Group with the Agent’s recommendation for the proposal along with any other relevant materials, including the basis for the analyst’s recommendation. The Proxy Administrator will then instruct the Agent to vote the proxy in the manner determined by the Global Proxy Group. A similar process will be followed if the Agent has a conflict of interest with respect to a proxy. The investment adviser will report to the Fund’s Board any votes cast contrary to the Guidelines or Agent recommendations, as applicable, no less than annually.

The investment adviser’s Global Proxy Group is responsible for monitoring and resolving possible material conflicts with respect to proxy voting. Because the Guidelines are predetermined and designed to be in the best interests of shareholders, application of the Guidelines to vote client proxies should, in most cases, adequately address any possible conflict of interest. The investment adviser will monitor situations that may result in a conflict of interest between any of its clients and the investment adviser or any of its affiliates by maintaining a list of significant existing and prospective corporate clients. The Proxy Administrator will compare such list with the names of companies of which he or she has been referred a proxy statement (the “Proxy Companies”). If a company on the list is also a Proxy Company, the Proxy Administrator will report that fact to the Global

Proxy Group. If the Proxy Administrator intends to instruct the Agent to vote in a manner inconsistent with the Guidelines, the Global Proxy Group will first determine, in consultation with legal counsel if necessary, whether a material conflict exists. If it is determined that a material conflict exists, the investment adviser will seek instruction on how the proxy should be voted from the Fund’s Board, or any committee or subcommittee identified by the Board. If a matter is referred to the Global Proxy Group, the decision made and basis for the decision will be documented by the Proxy Administrator and/or Global Proxy Group.

Information on how the Fund voted proxies relating to portfolio securities during the most recent 12 month period ended June 30 is available (1) without charge, upon request, by calling 1-800-262-1122, and (2) on the Securities and Exchange Commission’s website at http://www.sec.gov.

Item 8. Portfolio Managers of Closed-End Management Investment Companies

Eaton Vance Management (“EVM” or “Eaton Vance”) is the investment adviser of the Fund. EVM has engaged its affiliate, Parametric Portfolio Associates LLC (“Parametric”), as the sub-adviser of the Fund. Charles B. Gaffney, Douglas R. Rogers, CFA, CMT and Thomas C. Seto comprise the investment team responsible for the overall and day-to-day management of the Fund’s investments.

Messrs. Gaffney and Rogers are Vice Presidents of Eaton Vance, have managed other Eaton Vance portfolios for more than five years, and have been portfolio managers of the Fund since May 2023.

Mr. Seto is Head of Investment Management at Parametric, has managed other Eaton Vance portfolios for more than five years and has been a portfolio manager of the Fund since April 2005.

The following table shows, as of June 30, 2023, the number of accounts each portfolio manager managed in each of the listed categories and the total assets (in millions of dollars) in the accounts managed within each category. The table also shows the number of accounts with respect to which the advisory fee is based on the performance of the account, if any, and the total assets (in millions of dollars) in those accounts.

The following table shows, as of June 30, 2023, the dollar range of Fund shares beneficially owned by each portfolio manager.

Potential for Conflicts of Interest. It is possible that conflicts of interest may arise in connection with a portfolio manager’s management of the Fund’s investments on the one hand and the investments of other accounts for which a portfolio manager is responsible on the other. For example, a portfolio manager may have conflicts of interest in allocating management time, resources and investment opportunities among the Fund and other accounts he advises. In addition, due to differences in the investment strategies or restrictions between the Fund and the other accounts, the portfolio manager may take action with respect to another account that differs from the action taken with respect to the Fund. In some cases, another account managed by a portfolio manager may compensate the investment adviser based on the performance of the securities held by that account. The existence of such a performance based fee may create additional conflicts of interest for the portfolio manager in the allocation of management time, resources and investment opportunities. Whenever conflicts of interest arise, the portfolio manager will endeavor to exercise his discretion in a manner that he believes is equitable to all interested persons. EVM has adopted several policies and procedures designed to address these potential conflicts including a code of ethics and policies that govern the investment adviser’s trading practices, including among other things the aggregation and allocation of trades among clients, brokerage allocations, cross trades and best execution.

Compensation Structure for EVM

The compensation structure of Eaton Vance and its affiliates that are investment advisers (for purposes of this section “Eaton Vance”) is based on a total reward system of base salary and incentive compensation, which is paid either in the form of cash bonus, or for employees meeting the specified deferred compensation eligibility threshold, partially as a cash bonus and partially as mandatory deferred compensation. Deferred compensation granted to Eaton Vance employees is generally granted as a mix of deferred cash awards under the Investment Management Alignment Plan (IMAP) and equity-based awards in the form of stock units. The portion of incentive compensation granted in the form of a deferred compensation award and the terms of such awards are determined annually by the Compensation, Management Development and Succession Committee of the Board of Directors of Eaton Vance’s parent company, Morgan Stanley.

Base salary compensation. Generally, portfolio managers and research analysts receive base salary compensation based on the level of their position with the Adviser.

Incentive compensation. In addition to base compensation, portfolio managers and research analysts may receive discretionary year-end compensation. Incentive compensation may include:

Eaton Vance compensates employees based on principles of pay-for-performance, market competitiveness and risk management. Eligibility for, and the amount of any, discretionary compensation is subject to a multi-dimensional process. Specifically, consideration is given to one or more of the following factors, which can vary by portfolio management team and circumstances:

Further, the firm’s Global Incentive Compensation Discretion Policy requires compensation managers to consider only legitimate, business related factors when exercising discretion in determining variable incentive compensation, including adherence to Morgan Stanley’s core values, conduct, disciplinary actions in the current performance year, risk management and risk outcomes.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers

No such purchases this period.

Item 10. Submission of Matters to a Vote of Security Holders

No material changes.

Item 11. Controls and Procedures

(a) It is the conclusion of the registrant’s principal executive officer and principal financial officer that the effectiveness of the registrant’s current disclosure controls and procedures (such disclosure controls and procedures having been evaluated within 90 days of the date of this filing) provide reasonable assurance that the information required to be disclosed by the registrant has been recorded, processed, summarized and reported within the time period specified in the Commission’s rules and forms and that the information required to be disclosed by the registrant has been accumulated and communicated to the registrant’s principal executive officer and principal financial officer in order to allow timely decisions regarding required disclosure.

(b) There have been no changes in the registrant’s internal controls over financial reporting during the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12. Disclosure of Securities Lending Activities for Closed-End Management Investment Companies

No activity to report for the registrant’s most recent fiscal year end.

Item 13. Exhibits

Signatures

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Eaton Vance Tax-Managed Buy-Write Income Fund

Date: February 27, 2024

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Date: February 27, 2024

Date: February 27, 2024