; and (4) salaries and expenses for officers and personnel of the FHA. (e) Risk-Based premiums The FHA may, with respect to mortgages on 1- to 4-family residential properties insured by the FHA, establish a mortgage insurance premium structure involving a single premium payment collected prior to the insurance of the mortgage or annual payments (which may be collected on a periodic basis), or both. (f) Distributive shares (1) Requirement Upon any termination of the insurance obligation of the Mutual Mortgage Insurance Fund by payment of any mortgage insured thereunder, which termination occurs after the expiration of the 24-month period beginning on the date of the enactment of this Act, the FHA shall distribute to the mortgagor a share of the Participating Reserve Account of the Mutual Mortgage Insurance Fund in such manner and amount as the Secretary shall determine to be equitable and in accordance with sound actuarial and accounting practice. (2) Amount In no event shall any distributable share pursuant to paragraph (1) exceed the aggregate scheduled annual premiums of the mortgagor to the year of termination of the insurance. (3) Statute of limitations The Secretary shall not distribute any share to an eligible mortgagor under this subsection beginning on the date which is 6 years after the date the Secretary first transmitted written notification of eligibility to the last known address of the mortgagor, unless the mortgagor has applied in accordance with procedures prescribed by the Secretary for payment of the share within the 6-year period. (4) Applicability This subsection shall apply with respect only to mortgages insured under the Mutual Mortgage Insurance Fund after the date of the enactment of this Act. (g) Savings provision Nothing in this section may be construed to affect premiums charged for mortgage insurance provided for mortgages insured before the date of the enactment of this Act. (h) Limitation Nothing in this section shall permit or be construed to permit the FHA to apply different