24 C.F.R. § 242.20
An expired commitment may be reopened if a request for reopening is received by HUD no later than 90 days after the date of expiration of the commitment. The reopening request shall be accompanied by a fee of 50 cents per thousand dollars of the amount of the expired commitment. A commitment that has expired because of failure to pay the commitment fee may be reopened only upon payment of the commitment fee and the reopening fee. If the reopening request is not received by HUD within the required 90-day period, a new application accompanied by an application fee must be submitted. If a commitment for an increased amount has expired because of failure to pay an additional commitment fee based on the amount of the increase, the reopening fee shall be computed on the basis of the amount of the commitment increase rather than on the amount of the original commitment.
24 C.F.R. § 242.20