The tutorial shows how to build an amortization schedule in Excel to detail periodic payments on an amortizing loan or mortgage. Here is the link to my spreadsheet where you can calculate a loan over x years to be paid back monthly.It will give you the amortized payment amount. Loan amortization schedule. 3. 4, Enter values, Loan summary. Adding 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. I would like to be able to calculate the remaining amount of loan due after each payment on a loan with irregular payment dates and irregular amounts. No. Due Date, Due Payment, Extra Payment (Recurring), Extra Payment (Irregular), Interest Paid, Principal Paid, Balance. Call Meeting to Order. 2.