MSC INCOME FUND, INC.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of

the Securities Exchange Act of 1934 (Amendment No. )

Filed by the Registrant Q

Filed by a Party other than the Registranto

Check the appropriate box:

MSC Income Fund, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

May 20, 2026

Dear Stockholder:

You are cordially invited to attend the 2026 Annual Meeting of Stockholders of MSC Income Fund, Inc., which will be held on August 5, 2026, in the South Conference Room at 1330 Post Oak Boulevard, 2nd Floor, Houston, Texas 77056, commencing at 9:00 AM, local time. The notice of annual meeting and proxy statement following this letter describe the matters to be acted on at the Annual Meeting.

It is important that your shares be represented at the Annual Meeting and you are encouraged to vote your shares as soon as possible. The enclosed proxy card contains instructions for voting over the Internet, by telephone or by returning your proxy card via mail in the envelope provided. Your vote is important.

If your shares are held in book-entry form on the records of SS&C GIDS, Inc., MSC Income’s transfer agent and registrar, MSC Income has enclosed a proxy card for your use. You may vote these shares at the Annual Meeting or any adjournment or postponement thereof by completing and returning the proxy card or, alternatively, calling a toll-free telephone number or using the Internet as described on the proxy card. If a broker or other nominee holds your shares in “street name,” your broker has enclosed a voting instruction form, which you should use to vote those shares. The voting instruction form indicates whether you have the option to vote those shares by telephone or by using the Internet.

Thank you for your support.

Sincerely yours,

DWAYNE L. HYZAK

Chairman of the Board and Chief Executive Officer

YOUR VOTE IS IMPORTANT.

Whether or not you plan to attend the Annual Meeting, please take a few minutes now to vote your shares.

Important Notice Regarding the Availability of Proxy Materials for the 2026 Annual Meeting of Stockholders to Be Held on August 5, 2026.

MSC Income’s proxy statement and annual report on Form 10-K for the year ended December 31, 2025 are available on the Internet atwww.mscincomefund.com under “SEC Filings” in the “Investors” section of its website.

The following information applicable to the Annual Meeting may be found in the proxy statement and accompanying proxy card:

•the date, time and location of the Annual Meeting;

•a list of the matters intended to be acted on and the Board of Directors’ recommendations regarding those matters;

•any control/identification numbers that you need to access your proxy card; and

•information about attending the Annual Meeting and voting in person.

NOTICE OF 2026 ANNUAL MEETING OF STOCKHOLDERS

The 2026 Annual Meeting of Stockholders of MSC Income Fund, Inc., a Maryland corporation (“MSC Income” or the “Fund”), will be held in the South Conference Room at 1330 Post Oak Boulevard, 2nd Floor, Houston, Texas 77056, on August 5, 2026, at 9:00 AM local time, in order to:

(1)elect MSC Income’s directors for a term of one year;

(2)authorize flexibility for MSC Income, with the approval of the Board of Directors, to offer and sell shares of its common stock at a price below net asset value per share during the next 12 months following stockholder approval, subject to certain limitations described in the proxy statement; and

(3)transact such other business as may properly come before the Annual Meeting or any postponement or adjournment thereof.

If you were a stockholder as of the close of business on May 18, 2026, you are entitled to vote at the Annual Meeting and at any postponement or adjournment thereof.

Please indicate your vote as to the matters to be acted on at the Annual Meeting by following the instructions provided in the enclosed proxy card or voting instruction form, whether or not you plan on attending the Annual Meeting. If you plan to attend the Annual Meeting and wish to vote or change your vote there, please review the instructions set forth in the accompanying proxy statement under the caption “Voting Information.”

MSC Income has enclosed with this notice and proxy statement a copy of MSC Income’s annual report on Form 10-K for the year ended December 31, 2025.

By Order of the Board of Directors,

JASON B. BEAUVAIS

Executive Vice President, General Counsel and Secretary

PROXY STATEMENT FOR 2026 ANNUAL MEETING OF STOCKHOLDERS

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PROXY STATEMENT

2026 ANNUAL MEETING OF STOCKHOLDERS