(a) All of the provisions of §§ 203.260 through 203.295 of this chapter relating to mortgage insurance premiums shall apply to mortgages insured under this subpart, except that as to mortgages meeting the special requirements of § 221.60 or § 221.65, such provisions shall only be applicable under the circumstances prescribed in paragraph (b) of this section. Notwithstanding any provision in the mortgage instrument, there shall be no adjusted mortgage insurance premium or voluntary termination charge due the Commissioner on account of the prepayment of any mortgage or the voluntary termination of any mortgage insurance contract where (1) The mortgage is prepaid in full, or (2) the Commissioner receives a request for voluntary termination on or after May 1, 1972.

(b) Whenever the interest rate on a mortgage insured under this part as having met the special requirement of § 221.60 or § 221.65 shall have been increased to the maximum rate in accordance with § 221.60(j), § 221.65(d)(4), or § 221.65(d)(5), the provisions of §§ 203.260 through 203.295 of this chapter relating to mortgage insurance premiums shall apply except that:

(1) References to the original principal amount shall be construed as the scheduled unpaid principal balance, without taking into account delinquent payments or prepayments, on the date of the change in interest rate required under the mortgage.

(2) References to the date of the issuance of a Mortgage Insurance Certificate or the date of the endorsement of the credit instrument or the date the insurance becomes effective shall be construed as the date of the change in interest required under the mortgage.

(3) References to the first year of amortization under the mortgage shall be construed as the period beginning on the date of the change in interest rate required under the mortgage and ending on the next anniversary of the beginning of amortization.