24 CFR § 201.41 - Loan servicing.

(a) Generally. The lender shall service loans in accordance with accepted practices of prudent lending institutions. It shall have adequate facilities for contacting the borrower in the event of default, and shall otherwise exercise diligence in collecting the amount due. The lender shall remain responsible to the Secretary for proper collection efforts, even though actual loan servicing and collection may be performed by an agent of the lender. The lender shall have an organized means of identifying, on a periodic basis, the payment status of delinquent loans to enable collection personnel to initiate and follow-up on collection activities, and shall document its records to reflect its collection activities on delinquent loans.

(b) Partial payments. The lender shall accept any partial payment (inclusive of late charges) under an executed modification agreement or an acceptable repayment plan, and either apply it to the borrower's account or hold it in a trust account pending disposition. When partial payments held for disposition aggregate a full monthly installment, they shall be applied to the borrower's account, thus advancing the date of the oldest unpaid installment. If a partial payment is received more than 60 days after the date of default and was not submitted under a repayment plan or a modification agreement, the partial payment may be returned to the borrower, with a letter of explanation.