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. Construct a loan amortization schedule given the principal loan amount, periodic interest rate, and term (no. Of periodic payments) in Excel.