; in the case of a 3-family residence, 125 percent of the median 3-family house price in the eligible city or county in which the residence is located, as defined by the Secretary; and in the case of a 4-family residence, 125 percent of the median 4-family house price in the eligible city or county in which the residence is located, as defined by the Secretary. For the purposes of the preceding sentence, the term eligible city or county means a metropolitan city or urban county (as such terms are defined in section 102 of the Housing and Community Development Act of 1974 ( 42 U.S.C. 5302 )) that has a median 1-family home price that exceeds the amount determined under subparagraph (A)(ii) of this paragraph for the area (as the term is defined in the first sentence after subparagraph (B)) within which such city or county is located and is located in an area that, as determined by the Secretary, experienced a decrease in maximum principal obligation amount under this paragraph for 1-family residences equal to or in excess of 20 percent between January 1, 2013, and January 1, 2014. . 3. Effective date The amendment made by this Act shall apply only to mortgages for which the mortgagee has issued credit approval for the borrower on or after January 1, 2021.