The loan is large and deferral period 24 months. The tutorial shows how to build an amortization schedule in Excel to detail periodic payments on an amortizing loan or mortgage.I need to build an amortization schedule for a 30year loan. It's based on 12 payments and the loan documents have the payment amount. Fill in the column titled "Period" with your payment dates. Input the month and year for the first payment loan within cell A8.