The scheduled installment earnings method is a method to compute an interest charge by applying a daily rate to the unpaid balance of the amount financed as if each payment will be made on its scheduled installment date. A payment received before or after the due date does not affect the amount of the scheduled principal reduction.
The true daily earnings method is a method to compute an interest charge by applying a daily rate to the unpaid balance of the amount financed. The earned finance charge is computed by multiplying the daily rate by the number of days the actual principal balance is outstanding.