Please refer to #17 “Time Price Differential (TPD)” on the Security Agreement Retail Installment Contract:
The parties agree that the term of the contract, the effective daily (TPD) shall be based on your interest rate per annum, accrued daily on the unpaid balance. Delayed payments (extensions) and/or late payments will cause the actual aggregate (TPD) to be different than disclosed, resulting in a larger final “balloon” payment at maturity.