D.C. Mun. Regs. tit. 6, r. 6-B4021
If an employee received a travel advance, the employee must file a travel expense reimbursement form even if the employee is not seeking reimbursement above the advance amount, in order to reconcile actual expenditures against the advance.
If the amount advanced is less than the amount of the total actual and authorized expenses for which reimbursement is claimed, the employee shall be reimbursed the net difference.
If the advance exceeds the total actual and authorized expenses for which reimbursement is claimed, the employee must refund the excess by cash or check, or through payroll deduction. The refund or authorization to refund the excess through payroll deduction shall accompany the travel expense reimbursement form.
If an employee provides a refund to the District using a check, and the check is dishonored by the issuing financial institution, the employee shall be liable to the District for any resulting fees authorized by Section 1044(b) of the Delinquent Debt Recovery Act of 2012, effective September 20, 2012 (D.C. Law 19-168; D.C. Official Code § 1-350.03 ).
Except when there is good cause, an advance shall be revoked and the employee shall be required to reimburse the agency for the full advance, if the employee does not file a claim for reimbursement within ten (10) business days after travel is completed.
If funds are advanced to an employee and the employee does not travel, fails to submit a properly completed travel expense reimbursement form by the required date and thereafter fails to reimburse the agency for the full advance, or fails to reimburse the District for any advance in excess of actual and authorized expenses as required by § 4021.5, the agency shall take steps to collect the debt, including an offset against the employee's salary, a retirement credit, or other amount owed to the employee or any other legal method of recovery.
D.C. Mun. Regs. tit. 6, r. 6-B4021