D.C. Mun. Regs. tit. 16, r. 16-329
Except as otherwise provided in § 330, all payments scheduled to be made under any instrument of security shall be in equal amounts and at regular intervals.
The regular intervals shall be monthly, semimonthly, biweekly, or weekly.
Each retail installment contract shall set forth, under the caption "TERMS OF PAYMENT OF TIME PRICE BALANCE," the number of installment payments, the amount of each installment, the interval between the installment payments, the date on which the first installment shall be payable and, if it shall be less than the other installments, the amount of the final installment, which must be paid by the buyer in order to discharge in full the "TIME PRICE BALANCE" as set forth in the retail installment contract.
If, pursuant to statute or this chapter, the installments (other than the final installment) are not equal in amount, or if the intervals between installments are not regular for all installments, then there shall be included under the caption "TERMS OF PAYMENT OF TIME PRICE BALANCE" a schedule or statement showing the amount of each installment and the due date of each installment.
No person shall include in any promissory note, payment of which is secured by a retail installment contract, any provision, term, or condition of payment which varies materially from any provision, term, or condition of payment set forth in that retail installment contract.
If any promissory note contains any provision, term, or condition of payment which varies in any material particular from the provisions, terms, or conditions of payment set forth in the retail installment contract, that provision, term, or condition of payment of the promissory note shall be deemed to be the provision, term, or condition of payment set forth in the retail installment contract.
D.C. Mun. Regs. tit. 16, r. 16-329