UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED

MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number 811-09475

Nuveen AMT-Free Municipal Credit Income Fund

(Exact name of registrant as specified in charter)

Nuveen Investments

333 West Wacker Drive

Chicago, IL 60606

(Address of principal executive offices) (Zip code)

Mark L. Winget

Nuveen Investments

333 West Wacker Drive

Chicago, IL 60606

(Name and address of agent for service)

Registrant’s telephone number, including area code: (312) 917-7700

Date of fiscal year end: October 31

Date of reporting period: April 30, 2022

Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. ss. 3507.

ITEM 1. REPORTS TO STOCKHOLDERS.

     IMPORTANT DISTRIBUTION NOTICE

for Shareholders of the Nuveen Dynamic Municipal Opportunity Fund (NDMO) Semiannual Shareholder Report for the period ending April 30, 2022

The Nuveen Dynamic Municipal Opportunity Fund (NDMO) seeks to offer attractive cash flow to its shareholders, by converting the expected long-term total return potential of the Fund’s portfolio of investments into regular monthly distributions. Following is a discussion of the Managed Distribution Policy the Fund uses to achieve this.

The Fund pays monthly common share distributions that seek to convert the Fund’s expected long-term total return potential into regular cash flow. As a result, the Fund’s regular common share distributions (presented $0.0765 per share) may be derived from a variety of sources, including:

• net investment income consisting of regular interest and dividends,

• realized capital gains or,

• possibly, returns of capital representing in certain cases unrealized capital appreciation.

Such distributions are sometimes referred to as “managed distributions.” The Fund seeks to establish a distribution rate that roughly corresponds to the Adviser’s projections of the total return that could reasonably be expected to be generated by the Fund over an extended period of time. The Adviser may consider many factors when making such projections, including, but not limited to, long-term historical returns for the asset classes in which the Fund invests. As portfolio and market conditions change, the distribution amount and distribution rate on the Common Shares under the Fund’s Managed Distribution Policy could change.

When it pays a distribution, the Fund provides holders of its Common Shares a notice of the estimated sources of the Fund’s distributions (i.e., what percentage of the distributions is estimated to constitute ordinary income, short-term capital gains, long-term capital gains, and/or a non-taxable return of capital) on a year-to-date basis. It does this by posting the notice on its website (www.nuveen.com/cef), and by sending it in written form.

You should not draw any conclusions about the Fund’s investment performance from the amount of this distribution or from the terms of the Fund’s Managed Distribution Policy. The Fund’s actual financial performance will likely vary from month-to-month and from year-to-year, and there may be extended periods when the distribution rate will exceed the Fund’s actual total returns. The Managed Distribution Policy provides that the Board may amend or terminate the Policy at any time without prior notice to Fund shareholders. There are presently no reasonably foreseeable circumstances that might cause the Fund to terminate its Managed Distribution Policy.

Table of Contents

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Chair’s Letter

to Shareholders

Dear Shareholders,

Markets have had a turbulent start to 2022. Global economic activity has been deteriorating from post-pandemic peaks, and crisis-era monetary and fiscal support programs are being phased out. Inflation has surged partially due to supply chain bottlenecks and exacerbated by Russia’s war in Ukraine and recent lockdowns across China to contain a large-scale COVID-19 outbreak.

We are now almost four months into the Eastern European conflict and are witnessing the scale of the humanitarian crisis and the economic impact caused by this event. Market uncertainty has remained elevated, as the situations in Russia/Ukraine and China have increased inflation and recession risks. The U.S. Federal Reserve (Fed) and other central banks now face an even more difficult task of slowing inflation without pulling the economy into recession. As anticipated, the Fed began the rate hiking cycle in March 2022, raising its short-term rate by 0.25% from near zero for the first time since the pandemic was declared two years ago, then made increasingly more aggressive moves of 0.50% in May and 0.75% in June 2022. Additional rate hikes of these larger magnitudes are expected this year, as inflation has lingered at a 40-year high and consumer sentiment indicators are slumping. Forecasting was made difficult given the wide range of potential outcomes with regard to the Russia-Ukraine war, the resilience of China’s economy, the reopening of supply chains, the impact of inflation on economic growth, and the Fed’s response to inflation. Accordingly, markets are struggling with pricing these risks.

In the meantime, while markets will likely continue fluctuating with the daily headlines, we encourage investors to keep a long-term perspective. To learn more about how well your portfolio is aligned to your time horizon, risk tolerance and investment goals, consider reviewing it with your financial professional.

On behalf of the other members of the Nuveen Fund Board, I look forward to continuing to earn your trust in the months and years ahead.

Terence J. Toth

Chair of the Board

June 22, 2022

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Important Notices

For Shareholders of

Nuveen AMT-Free Municipal Credit Income Fund (NVG)
Nuveen Municipal Credit Income Fund (NZF)
Nuveen Municipal High Income Opportunity Fund (NMZ)
Nuveen Municipal Credit Opportunities Fund (NMCO)
Nuveen Dynamic Municipal Opportunities Fund (NDMO)

Portfolio Manager Commentaries in Semiannual Reports

The Funds include portfolio manager commentary in their annual shareholder reports. For the Fund’s most recent annual portfolio manager discussion, please refer to the Portfolio Managers’ Comments section of the Fund’s October 31, 2021 annual shareholder report.

For current information on your Fund’s investment objectives, portfolio management team and average annual total returns please refer to the Fund’s website at www.nuveen.com.

For changes that occurred to your Fund both during and subsequent to this reporting period, please refer to the Notes to Financial Statements section of this report.

For average annual total returns as of the end of this reporting period, please refer to the Performance Overview and Holding Summaries section within this report.

Fund Reorganization

Effective prior to the opening of business on June 6, 2022, Nuveen Enhanced Municipal Value Fund (NEV) was reorganized into NZF (the “Reorganization”). Refer to Note 1 and Note 11 of the Notes to Financial Statements within this report for further details on the Reorganization.

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Fund Leverage

IMPACT OF THE FUNDS’ LEVERAGE STRATEGIES ON PERFORMANCE

One important factor impacting the returns of the Funds’ common shares relative to their comparative benchmarks was the Funds’ use of leverage through their issuance of preferred shares, reverse repurchase agreements, borrowings and/or investments in inverse floating rate securities, which represent leveraged investments in underlying bonds. The Funds use leverage because our research has shown that, over time, leveraging provides opportunities for additional income. The opportunity arises when short-term rates that a Fund pays on its leveraging instruments are lower than the interest a Fund earns on its portfolio of long-term bonds that it has bought with the proceeds of that leverage. This has been particularly true in the recent market environment where short-term rates have been low by historical standards.

However, use of leverage can expose Fund common shares to additional price volatility. When a Fund uses leverage, the Fund’s common shares will experience a greater increase in their net asset value if the municipal bonds acquired through the use of leverage increase in value, but will also experience a correspondingly larger decline in their net asset value if the bonds acquired through leverage decline in value. All this will make the shares’ total return performance more variable over time.

In addition, common share income in levered funds will typically decrease in comparison to unlevered funds when short-term interest rates increase and increase when short-term interest rates decrease. In recent quarters, fund leverage expenses have generally tracked the overall movement of short-term tax-exempt interest rates. While fund leverage expenses are somewhat higher than their recent lows, leverage nevertheless continues to provide the opportunity for incremental common share income, particularly over longer-term periods.

The use of leverage had a negative impact on the total return performance of the Funds over the reporting period.

As of April 30, 2022, the Funds’ percentages of leverage are as shown in the accompanying table.

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THE FUNDS’ REGULATORY LEVERAGE

As of April 30, 2022, the following Funds have issued and outstanding preferred shares as shown in the accompanying table.

Refer to Notes to Financial Statements, Note 5 – Fund Shares for further details on preferred shares and each Fund’s respective transactions.

Reverse Repurchase Agreements

As noted previously, during the current fiscal period, NMZ and NDMO used reverse repurchase agreements, in which each Fund sells to a counterparty a security that it holds with a contemporaneous agreement to repurchase the same security at an agreed upon price and date. The Funds’ transactions in reverse repurchase agreements are as shown in the accompanying table.

Refer to Notes to Financial Statements, Note 9 – Borrowing Arrangements for further details.

Bank Borrowings

As noted previously, NDMO employs leverage through the use of bank borrowings. The Fund’s bank borrowing activities are as shown in the accompanying table. Paydowns reflect on-going leverage management activity that seeks to maintain the Fund’s leverage ratio within a specified internal operating range.

Refer to Notes to Financial Statements, Note 9 – Borrowing Arrangements for further details.

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Common Share Information

NVG, NZF, NMZ and NMCO COMMON SHARE DISTRIBUTION INFORMATION

The following information regarding the distributions for NVG, NZF, NMZ and NMCO are current as of April 30, 2022. Each Fund’s distribution levels may vary over time based on each Fund’s investment activity and portfolio investments value changes.

During the current reporting period, each Fund’s distributions to common shareholders were as shown in the accompanying table.

NVG, NZF, NMZ and NMCO seek to pay regular monthly dividends out of its net investment income at a rate that reflects its past and projected net income performance. To permit each Fund to maintain a more stable monthly dividend, the Fund may pay dividends at a rate that may be more or less than the amount of net income actually earned by the Fund during the period. Distributions to common shareholders are determined on a tax basis, which may differ from amounts recorded in the accounting records. In instances where the monthly dividend exceeds the earned net investment income, the Fund would report a negative undistributed net ordinary income. Refer to Note 6 — Income Tax Information for additional information regarding the amounts of undistributed net ordinary income and undistributed net long-term capital gains and the character of the actual distributions paid by the Fund during the period.

All monthly dividends paid by NVG, NZF, NMZ and NMCO during the current reporting period were paid from net investment income. If a portion of the Fund’s monthly distributions is sourced or comprised of elements other than net investment income, including capital gains and/or a return of capital, shareholders will be notified of those sources. For financial reporting purposes,

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the per share amounts of each Fund’s distributions for the reporting period are presented in this report’s Financial Highlights. For income tax purposes, distribution information for each Fund as of its most recent tax year end is presented in Note 6 — Income Tax Information within the Notes to Financial Statements of this report.

COMMON SHARE DISTRIBUTION INFORMATION FOR NDMO

This notice provides shareholders with information regarding fund distributions, as required by current securities laws. You should not draw any conclusions about the Fund’s investment performance from the amount of this distribution or from the terms of the Fund’s Managed Distribution Policy.

The following table provides estimates of the Fund’s distribution sources, reflecting year-to-date cumulative experience through the month-end prior to the latest distribution. The Fund attributes these estimates equally to each regular distribution throughout the year. Consequently, the estimated information as of the specified month-end shown below is for the current distribution, and also represents an updated estimate for all prior months in the year. For all funds, it is estimated that the funds have distributed more than their income and net realized capital gains; therefore, a portion of the distributions may be (and is shown below as being estimated to be) a return of capital. A return of capital may occur, for example, when some or all of the money that you invested in the Fund is paid back to you. A return of capital distribution does not necessarily reflect the Fund’s investment performance and should not be confused with “yield” or “income.”

The amounts and sources of distributions reported in this 19(a) Notice are only estimates and are not being provided for tax reporting purposes. The actual amounts and sources of the amounts for tax reporting purposes will depend upon the Fund’s investment experience during the remainder of its fiscal year and may be subject to changes based on tax regulations. The Fund will send a Form 1099-DIV for the calendar year that will tell you how to report these distributions for federal income tax purposes. More details about the Fund’s distributions and the basis for these estimates are available on www.nuveen.com/cef.

Data as of April 30, 2022

The following table provides information regarding the Fund’s distributions and total return performance over various time periods. This information is intended to help you better understand whether the Fund’s returns for the specified time periods were sufficient to meet its distributions.

Data as of April 30, 2022

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Common Share Information (continued)

NUVEEN CLOSED-END FUND DISTRIBUTION AMOUNTS

The Nuveen Closed-End Funds’ monthly and quarterly periodic distributions to shareholders are posted on www.nuveen.com and can be found on Nuveen’s enhanced closed-end fund resource page, which is at https://www.nuveen.com/resource-center-closedendfunds, along with other Nuveen closed-end fund product updates. To ensure timely access to the latest information, shareholders may use a subscribe function, which can be activated at this web page (https://www.nuveen.com/subscriptions).

COMMON SHARE EQUITY SHELF PROGRAM

During the current reporting period, NVG, NMZ, NMCO and NDMO were authorized by the Securities and Exchange Commission (SEC) to issue additional common shares through an equity shelf program (Shelf Offering). Under these programs, NVG, NMZ, NMCO and NDMO, subject to market conditions, may raise additional capital from time to time in varying amounts and offering methods at a net price at or above each Fund’s NAV per common share. The maximum aggregate offering under these Shelf Offerings, are as shown in the accompanying table.

During the current reporting period, NMZ, NMCO and NDMO sold common shares through their Shelf Offering at a weighted average premium to their NAV per common share as shown in the accompanying table.

Refer to Notes to Financial Statements, Note 5 – Fund Shares for further details on Shelf Offerings and each Fund’s transactions.

COMMON SHARE REPURCHASES

During August 2021, the Funds’ Board of Trustees reauthorized an open-market share repurchase program, allowing each Fund to repurchase an aggregate of up to approximately 10% of its outstanding common shares.

During the current reporting period, the Funds did not repurchase any of their outstanding common shares. As of April 30, 2022, (and since the inception of the Funds’ repurchase programs), each Fund has cumulatively repurchased and retired its outstanding common shares as shown in the accompanying table.

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OTHER COMMON SHARE INFORMATION

As of April 30, 2022, the Funds’ common share prices were trading at an average premium/(discount) to their common share NAVs and trading at an average premium/(discount) to NAV during the current reporting period, as follows.

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Refer to the Glossary of Terms Used in this Report for further definition of the terms used within this section.

Average Annual Total Returns as of April 30, 2022*

Past performance is not predictive of future results. Current performance may be higher or lower than the data shown. Returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Returns at NAV are net of Fund expenses, and assume reinvestment of distributions. Comparative index return information is provided for the Fund’s shares at NAV only. Indexes are not available for direct investment.

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This data relates to the securities held in the Fund’s portfolio of investments as of the end of the reporting period. It should not be construed as a measure of performance for the Fund itself. Holdings are subject to change.

The ratings disclosed are the lowest rating given by one of the following national rating agencies: Standard & Poor’s Group, Moody’s Investors Service, Inc. or Fitch, Inc. Credit ratings are subject to change. AAA, AA, A and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national rating agencies.

¹ See Portfolio of Investments for the states comprising “Other” and not listed in the States and Territories above.

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Refer to the Glossary of Terms Used in this Report for further definition of the terms used within this section.

Average Annual Total Returns as of April 30, 2022*

Past performance is not predictive of future results. Current performance may be higher or lower than the data shown. Returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Returns at NAV are net of Fund expenses, and assume reinvestment of distributions. Comparative index return information is provided for the Fund’s shares at NAV only. Indexes are not available for direct investment.

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This data relates to the securities held in the Fund’s portfolio of investments as of the end of the reporting period. It should not be construed as a measure of performance for the Fund itself. Holdings are subject to change.

The ratings disclosed are the lowest rating given by one of the following national rating agencies: Standard & Poor’s Group, Moody’s Investors Service, Inc. or Fitch, Inc. Credit ratings are subject to change. AAA, AA, A and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national rating agencies.

¹ See Portfolio of Investments for the states comprising “Other” and not listed in the States and Territories above.

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Refer to the Glossary of Terms Used in this Report for further definition of the terms used within this section.

Average Annual Total Returns as of April 30, 2022*

* For purposes of Fund performance, relative results are measured against the S&P Municipal Yield Index. Prior to 9/8/20, the Fund’s performance was measured against the S&P Municipal Bond High Yield Index.

Past performance is not predictive of future results. Current performance may be higher or lower than the data shown. Returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Returns at NAV are net of Fund expenses, and assume reinvestment of distributions. Comparative index return information is provided for the Fund’s shares at NAV only. Indexes are not available for direct investment.

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This data relates to the securities held in the Fund’s portfolio of investments as of the end of the reporting period. It should not be construed as a measure of performance for the Fund itself. Holdings are subject to change.

The ratings disclosed are the lowest rating given by one of the following national rating agencies: Standard & Poor’s Group, Moody’s Investors Service, Inc. or Fitch, Inc. Credit ratings are subject to change. AAA, AA, A and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national rating agencies.

¹ See Portfolio of Investments for the states comprising “Other” and not listed in the States and Territories above.

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Refer to the Glossary of Terms Used in this Report for further definition of the terms used within this section.

Average Annual Total Returns as of April 30, 2022*

* For purposes of Fund performance, relative results are measured against the S&P Municipal Yield Index.

Since inception returns are from 9/16/19. Past performance is not predictive of future results. Current performance may be higher or lower than the data shown. Returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Returns at NAV are net of Fund expenses, and assume reinvestment of distributions. Comparative index return information is provided for the Fund’s shares at NAV only. Indexes are not available for direct investment.

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This data relates to the securities held in the Fund’s portfolio of investments as of the end of the reporting period. It should not be construed as a measure of performance for the Fund itself. Holdings are subject to change.

The ratings disclosed are the lowest rating given by one of the following national rating agencies: Standard & Poor’s Group, Moody’s Investors Service, Inc. or Fitch, Inc. Credit ratings are subject to change. AAA, AA, A and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national rating agencies.

¹ See Portfolio of Investments for the states comprising “Other” and not listed in the States and Territories above.

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Refer to the Glossary of Terms Used in this Report for further definition of the terms used within this section.

Average Annual Returns as of April 30, 2022*

* For purposes of Fund performance, relative results are measured against the S&P Municipal Bond Index.

Since inception returns are from 8/26/20. Past performance is not predictive of future results. Current performance may be higher or lower than the data shown. Returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Returns at NAV are net of Fund expenses, and assume reinvestment of distributions. Comparative index return information is provided for the Fund’s shares at NAV only. Indexes are not available for direct investment.

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This data relates to the securities held in the Fund’s portfolio of investments as of the end of the reporting period. It should not be construed as a measure of performance for the Fund itself. Holdings are subject to change.

The ratings disclosed are the lowest rating given by one of the following national rating agencies: Standard & Poor’s Group, Moody’s Investors Service, Inc. or Fitch, Inc. Credit ratings are subject to change. AAA, AA, A and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below-investment grade ratings. Holdings designated N/R are not rated by these national rating agencies.

¹ See Portfolio of Investments for the states comprising “Other” and not listed in the States and Territories above.

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Shareholder Meeting Report

The annual meeting of shareholders was held on April 8, 2022 for NMCO.  The meeting was held virtually due to public health concerns regarding the ongoing COVID-19 pandemic; at this meeting the shareholders were asked to elect Board members. A special meeting of shareholders was held on April 29, 2022 for NZF. The meeting was held virtually due to public health concerns regarding the ongoing COVID-19 pandemic; at this meeting the preferred shareholders were asked to approve an Agreement and Plan of Reorganization.

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