According to e-AmortizationSchedule.com mortgage amortization is the reimbursement of principal from scheduled mortgage payments that exceed the interest due. The scheduled payment paid by the borrower less the interest equaling amortization. The loan balance declines by the amount of the amortization, plus the amount of any extra payment. Negative amortization occurs when the scheduled payment is less than the interest due whereby the balance goes up.

The Fully Amortizing Payment on FRM and ARM:

The fully amortizing payment is the monthly mortgage payment that will eventually pay off the loan at term. On a fixed rate mortgage (FRM), the fully amortizing payment is calculated at the outset and remains constant over the life of the loan. On the other hand, on an adjustable rate mortgage or ARM, the fully amortizing payment is constant only when the interest rate remains constant. The fully amortizing payment changes only when the rate changes.

Standard Mortgage Amortization:

In a standard mortgage, tax and insurance payments are shown in the amortization schedules, if made by the lender and the balance of the tax or insurance escrow account. Strict and rigid rules apply in the payment requirement regarding the standard mortgage. Even if a single payment is missed the late charges accumulate until the payment is made up.

Simple Interest Mortgage Amortization:

The interest is based on the balance of the day of payment on a simple interest mortgage, which is calculated daily. If payment were made on the first day of every month in both cases, it would come out the same over the course of a year. However, if a payment were late staying within the usual fifteen-day grace period under the standard mortgage scheme, one would do better with that mortgage.