Such a bank or savings and loan association may contract for and receive interest at the rate provided for in Chapter 33 of this subtitle, or, in lieu of such interest, a finance charge which, if expressed as an annual percentage rate, does not exceed a rate of 21% per annum on the unpaid balances of principal.
Finance charge
D.C. Code § 28-3602, under Direct Motor Vehicle Installment Loans..
D.C. Code § 28-3602