The tutorial shows how to build an amortization schedule in Excel to detail periodic payments on an amortizing loan or mortgage. 13, Payment number, Payment date, Beginning balance, Scheduled payment, Extra payment, TotalAdding extra principal payments in order to pay off the loan earlier than the loan contract calls for. In this tutorial we will add this feature. Loan Amortization Schedule outlines the interest and principal payments owed on a mortgage, including the outstanding balance.