D.C. Mun. Regs. tit. 19, r. 19-4387
The DCPL CPO shall charge interest on the daily balance of all advance payments at the rate of interest in the District allowed in judgments and decrees as set forth in the D.C. Official Code § 28-3302(c) (1981 ed.).
The interest rate for advance payments shall be adjusted for changes in the prime rate or any change in rate established under D.C. Official Code § 28-3302(c) (1981 ed.).
Interest shall be computed at the end of each month on the daily balance of advance payments at the applicable daily interest rate, unless the balance is repaid within thirty (30) days.
The DCPL CPO shall not allow interest charges for advance payments as reimbursable costs under cost-reimbursement contracts, whether the interest charge was incurred by the prime contractor or a subcontractor.
D.C. Mun. Regs. tit. 19, r. 19-4387