42 U.S. Code § 12808 - Second mortgage assistance for first-time homebuyers
(a) In general
The Secretary shall make available a model program under which units of general local government provide loans (secured by second mortgages) with deferred payment of interest and principal to first-time homebuyers.
(b) Homeownership counseling
The program under this section shall provide for homeownership counseling to first-time homebuyers assisted, which shall include—
(c) Eligibility requirements
Deferred payment loans secured by second mortgages may be provided under the model program under this section if—
(2) the property secured by the second mortgage is a single-family residence and is the principal residence of the homebuyer; and
(d) Payment terms
(1) Period of deferral
The payment of any principal and interest on a loan under this section shall be deferred for not less than the 5-year period beginning on the date of the acquisition of the residence by the homebuyer.
(2) Interest rate
The interest rate on the unpaid balance of a loan under this section shall be at least 4 percent.
A deferred payment loan assisted with amount  provided under a grant under this section shall be secured by a lien on the property involved, which lien shall be subordinate to the first mortgage on the property.
 So in original. Probably should be “amounts”.