12 U.S.C. § 1715z–1c

After December 1, 1987 , the Secretary of Housing and Urban Development shall control rents and charges as they were controlled prior to April 19, 1983 , for any multifamily housing project insured under the National Housing Act [ 12 U.S.C. 1701 et seq.] if— (1) during the period of April 19, 1983 , through December 1, 1987 , the project owner and the Secretary have not executed, and the project owner has not filed a written request with the Secretary to enter into, an amendment to the regulatory agreement pursuant to regulations published by the Secretary on April 19, 1983 , or June 4, 1986 , electing to deregulate rents or utilize an alternative formula for determining the maximum allowable rents pursuant to regulations published by the Secretary on April 19, 1983 , or June 4, 1986 ; and (2) (A) the project was, as of December 1, 1987 , receiving a housing assistance payment under a contract pursuant to section 1437f of title 42 (other than under the existing housing certificate program of section 1437f(b)(1) of title 42 ); or (B) not less than 50 percent of the units in the project are occupied by lower income families (as defined in section 1437a(a)(2) 1 1 Probably should be a reference to section 1437a(b)(2). of title 42).