FVGA [15] The future value of a constantly growing annuity is:

Where PMT₁is the first payment (next year), g is the growth rate in the annuity, r is the interest rate earned on investment, and n is the length of the growing annuity. This equation calculates the future value immediately after the last payment.make a spreadsheet that allows the user to enter an initial payment (PMT₁, the number of years, an interest rate, and a growth rate.The spreadsheet returns the Future Value of the Growing Annuity and an amortization schedule.Restrict n to being less than or equal to 20 years, and r>g.