TP Flexible Income Fund 10-Q 2022 Q2 Quarterly report

Exhibit 32.2

CERTIFICATION BY CHIEF FINANCIAL OFFICER

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report on Form 10-Q of Prospect Flexible Income Fund, Inc. (now known as Prospect Sustainable Income Fund, Inc.) (the “Company”) for the period ended December 31, 2021, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Kristin Van Dask, Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

1.The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

2.The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company as of the dates and for the periods expressed in the Report.

/s/ Kristin Van Dask

    Kristin Van Dask

    Chief Financial Officer

    (Principal Accounting and Financial Officer)

    Date: February 8, 2022