To assist in providing adequate housing for families of low and moderate income, particularly in suburban and outlying areas, this section is designed to supplement systems of mortgage insurance under other provisions of this chapter by making feasible the insurance of mortgages covering properties in areas where it is not practicable to obtain conformity with many of the requirements essential to the insurance of mortgages on housing in built-up urban areas. The Secretary is authorized, upon application by the mortgagee, to insure, as hereinafter provided, any mortgage (as defined in section 1707 of this title) offered to him which is eligible for insurance as hereinafter provided, and, upon such terms as the Secretary may prescribe, to make commitments for the insuring of such mortgages prior to the date of their execution or disbursement thereon: Provided, That the aggregate amount of principal obligations of all mortgages insured under this section and outstanding at any one time shall not exceed $100,000,000, except that with the approval of the President such aggregate amount may be increased at any time or times by additional amounts aggregating not more than $150,000,000 upon a determination by the President, taking into account the general effect of any such increase upon conditions in the building industry and upon the national economy, that such increase is in the public interest: And provided further, That no mortgage shall be insured under this section after August 2, 1954, except pursuant to a commitment to insure issued on or before such date.
The Secretary is authorized to fix a premium charge for the insurance of mortgages under this section, but in the case of any mortgage, such charge shall not be less than an amount equivalent to one-half of 1 per centum per annum nor more than an amount equivalent to 1 per centum per annum of the amount of the principal obligation of the mortgage outstanding at any time, without taking into account delinquent payments or prepayments. Such premium charges shall be payable by the mortgagee, either in cash or in debentures issued by the Secretary under this section at par plus accrued interest, in such manner as may be prescribed by the Secretary: Provided, That the Secretary may require the payment of one or more such premium charges at the time the mortgage is insured, at such discount rate as he may prescribe not in excess of the interest rate specified in the mortgage. If the Secretary finds, upon the presentation of a mortgage for insurance and the tender of the initial premium charge or charges so required, that the mortgage complies with the provisions of this section, such mortgage may be accepted for insurance by endorsement or otherwise as the Secretary may prescribe. In the event that the principal obligation of any mortgage accepted for insurance under this section is paid in full prior to the maturity date, the Secretary is further authorized, in his discretion, to require the payment by the mortgagee of an adjusted premium charge in such amount as the Secretary determines to be equitable, but not in excess of the aggregate amount of the premium charges that the mortgagee would otherwise have been required to pay if the mortgage had continued to be insured until such maturity date; and in the event that the principal obligation is paid in full as herein set forth, the Secretary is authorized to refund to the mortgagee for the account of the mortgagor all, or such portion as he shall determine to be equitable, of the current unearned premium charges theretofore paid.
The Secretary may, at any time under such terms and conditions as he may prescribe, consent to the release of the mortgagor from his liability under the mortgage or the credit instrument secured thereby, or consent to the release of parts of the mortgaged property from the lien of the mortgage.
Any contract of insurance executed by the Secretary under this section shall be conclusive evidence of the eligibility of the mortgage for insurance, and the validity of any contract of insurance so executed shall be incontestable in the hands of an approved mortgagee from the date of the execution of such contract, except for fraud or misrepresentation on the part of such approved mortgagee.
In any case in which the mortgagee under a mortgage insured under this section shall have foreclosed and taken possession of the mortgaged property in accordance with the regulations of, and within a period to be determined by, the Secretary or shall, with the consent of the Secretary, have otherwise acquired such property from the mortgagor after default, the mortgagee shall be entitled to receive the benefits of the insurance as provided in section 1710(a) of this title with respect to mortgages insured under section 203(b)(2)(D) of this Act.
Subsections (c), (d), (e), (f), (g), (h), (j), and (k)  of section 1710 of this title shall be applicable to mortgages insured under this section except that all references therein to the Mutual Mortgage Insurance Funds or the Fund shall be construed to refer to the General Insurance Fund, and all references therein to section 1709 of this title shall be construed to refer to this section: Provided, That debentures issued in connection with mortgages insured under this section shall have the same tax exemption as debentures issued in connection with mortgages insured under section 1709 of this title.