Loan Amortization Schedule with extra payments every period, variable periods in Excel - Office 365 In this accounting lesson, we explain and go through examples of a simple Loan Amortization Schedule with variable (changing) interest rate.The tutorial shows how to build an amortization schedule in Excel to detail periodic payments on an amortizing loan or mortgage. Create automatic loan amortization schedule table with PMT, IPMT, PPMT formulas in Microsoft Excel You can create an Excel amortization table with changing interest rates. Here's how you can build it. This calculator will help you figure out your regular loan payments and it will also create a detailed schedule of payments. A little formula creation trouble and how to figure out some logic to fix your formulas and custom number formatting.