BlackRock Advisors, LLC (“BlackRock”) announced today an investment policy update for BlackRock Muni Intermediate Duration Fund, Inc. (the “Fund”) (NYSE: MUI, CUSIP: 09253X102). The Fund’s Board of Directors has approved the elimination of the Fund’s non-fundamental policy to invest at least 80% of its assets in municipal bonds with a duration of three to ten years at the time of investment. The Fund expects to maintain a dollar-weighted average portfolio duration, as calculated by the investment adviser, of three to ten years, under its current investment policies.

About BlackRock

BlackRock’s purpose is to help more and more people experience financial well-being. As a fiduciary to investors and a leading provider of financial technology, our clients turn to us for the solutions they need when planning for their most important goals. As of December 31, 2019, the firm managed approximately $7.43 trillion in assets on behalf of investors worldwide. For additional information on BlackRock, please visit www.blackrock.com/corporate | Twitter: @blackrock | Blog: www.blackrockblog.com | LinkedIn: www.linkedin.com/company/blackrock.

Availability of Fund Updates

BlackRock will update performance and certain other data for the Fund on a monthly basis on its website in the “Closed-end Funds” section of www.blackrock.com as well as certain other material information as necessary from time to time. Investors and others are advised to check the website for updated performance information and the release of other material information about the Fund. This reference to BlackRock’s website is intended to allow investors public access to information regarding the Fund and does not, and is not intended to, incorporate BlackRock’s website in this release.

Forward-Looking Statements

This press release, and other statements that BlackRock or the Fund may make, may contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act, with respect to the Fund’s or BlackRock’s future financial or business performance, strategies or expectations. Forward-looking statements are typically identified by words or phrases such as “trend,” “potential,” “opportunity,” “pipeline,” “believe,” “comfortable,” “expect,” “anticipate,” “current,” “intention,” “estimate,” “position,” “assume,” “outlook,” “continue,” “remain,” “maintain,” “sustain,” “seek,” “achieve,” and similar expressions, or future or conditional verbs such as “will,” “would,” “should,” “could,” “may” or similar expressions.

BlackRock cautions that forward-looking statements are subject to numerous assumptions, risks and uncertainties, which change over time. Forward-looking statements speak only as of the date they are made, and BlackRock assumes no duty to and does not undertake to update forward-looking statements. Actual results could differ materially from those anticipated in forward-looking statements and future results could differ materially from historical performance.

With respect to the Fund, the following factors, among others, could cause actual events to differ materially from forward-looking statements or historical performance: (1) changes and volatility in political, economic or industry conditions, the interest rate environment, foreign exchange rates or financial and capital markets, which could result in changes in demand for the Fund or in the Fund’s net asset value; (2) the relative and absolute investment performance of the Fund and its investments; (3) the impact of increased competition; (4) the unfavorable resolution of any legal proceedings; (5) the extent and timing of any distributions or share repurchases; (6) the impact, extent and timing of technological changes; (7) the impact of legislative and regulatory actions and reforms, including the Dodd-Frank Wall Street Reform and Consumer Protection Act, and regulatory, supervisory or enforcement actions of government agencies relating to the Fund or BlackRock, as applicable; (8) terrorist activities, international hostilities, health epidemics and natural disasters, which may adversely affect the general economy, domestic and local financial and capital markets, specific industries or BlackRock; (9) BlackRock’s ability to attract and retain highly talented professionals; (10) the impact of BlackRock electing to provide support to its products from time to time; and (11) the impact of problems at other financial institutions or the failure or negative performance of products at other financial institutions.

Annual and Semi-Annual Reports and other regulatory filings of the Fund with the SEC are accessible on the SEC’s website atwww.sec.gov and on BlackRock’s website at www.blackrock.com, and may discuss these or other factors that affect the Fund. The information contained on BlackRock’s website is not a part of this press release.