The tutorial shows how to build an amortization schedule in Excel to detail periodic payments on an amortizing loan or mortgage. Fill in the column titled "Period" with your payment dates.Input the month and year for the first payment loan within cell A8. Loan amortization schedule. 3. 4, Enter values, Loan summary. Does anyone know how to calculate the principal and interest payments after a one time extra principal payment on a mortgage in excel? This Excel spreadsheet makes it easy to view the amortization of a home loan with optional extra monthly payments. This template will help you calculate loan and interest balances, accrued interest at any point in time on loans granted or issued. This video provides a basic introduction into the top 10 most important formulas used in excel. This template will help you calculate loan and interest balances, accrued interest at any point in time on loans granted or issued.