45 C.F.R. § 1609.5

(a) When a case results in recovery of damages or statutory benefits, a recipient may accept reimbursement from the client for out-of-pocket costs and expenses incurred in connection with the case, if the client has agreed in writing to reimburse the recipient for such costs and expenses out of any such recovery.

(b) A recipient may require a client to pay court costs when the client does not qualify to proceed in forma pauperis under the rules of the jurisdiction.

[75 FR 6818, Feb. 11, 2010, as amended at 82 FR 20447, May 2, 2017]