Suppose that youd like to retire in 40 years and you want to have a future value of $ 400000 in a savings account. Also suppose that your employer makes regular monthly payments into your retirement account If you can expect an APR of 9% for your account, how much do you need your employer to deposit each month? Employer Contribution The formulas we have been using assume that the interest rate is constant over the period in question. Over a period of 40 years, though, interest rates can vary widely. To see what difference the interest rate can make, lets assume a constant APR of 5% for your retirement account. How much do you need your employer to deposit each month unde this assumption? Employer Contribution