24 C.F.R. § 266.608
If the contract of insurance is terminated by payment in full or is terminated by the HFA on a form prescribed by the Commissioner, after the date of the first payment to principal, the Commissioner shall refund any mortgage insurance premium for the period after the effective date of the termination of insurance. The refund shall be mailed to the HFA for credit to the mortgagor's account. In computing the pro rata portion of the annual mortgage insurance premium, the date of termination of insurance shall be the last day of the month in which the mortgage is prepaid or the Commissioner receives a notification of termination, whichever is later. No refund shall be made if the insurance was terminated because of the submission of an application for initial claim payment or if the termination occurs before the date of the first payment to principal.
24 C.F.R. §266.608