24 C.F.R. § 291.555 – Refinancing.

(a) General. A law enforcement officer, teacher, or firefighter/emergency medical technician may refinance the mortgage and note used to purchase the home. However, the total of the refinanced mortgage and the remaining principal balance of the second mortgage may not exceed 95 percent of the value of the property, as appraised at the time of the refinancing. Unless HUD permits subordination pursuant to paragraph (b) of this section, the second mortgage described in § 291.550 must hold a superior lien position to the refinanced mortgage.
(b) Subordination of second mortgage. HUD may permit subordination of the second mortgage to the refinanced mortgage, but only if HUD, at its sole discretion, determines that the refinancing will satisfy one of the following:
1. (1) Will result in a lower annual percentage rate (APR) on the first mortgage;
2. (2) Will be undertaken pursuant to HUD's Section 203(k) Rehabilitation Loan Insurance Program in order to rehabilitate or repair the home; or
3. (3) Is necessary to prevent the law enforcement officer, teacher, or firefighter/emergency medical technician from defaulting on the first mortgage.