24 CFR § 203.405 - Debenture interest rate.
(a) Debentures shall bear interest from the date of issue, payable semiannually on the first day of January and the first day of July of each year at the rate in effect as of the day the commitment was issued, or as of the date the mortgage was endorsed for insurance, whichever rate is higher. For applications involving mortgages originated under the single family Direct Endorsement program, debentures shall bear interest from the date of issue, payable semiannually on the first day of January and on the first day of July of each year at the rate in effect as of the date the mortgage was endorsed for insurance;
(b) For mortgages endorsed for insurance after January 23, 2004, if an insurance claim is paid in cash, the debenture interest rate for purposes of calculating such a claim shall be the monthly average yield, for the month in which the default on the mortgage occurred, on United States Treasury Securities adjusted to a constant maturity of 10 years.