How Much Income Do You Need To Qualify? In order to figure out if you qualify for a mortgage, lenders use two ratios. The first one, called the front ratio, is used to check your monthly payment including taxes and insurance against your monthly income. The other ratio, the back ratio, checks total monthly expenses including the monthly payment against your monthly income. Principle Balance:    $ Down Payment:    $ Length of Mortgage:      years Interest Rate:      % Estimated Monthly Taxes:    $ Estimated Monthly Insurance:    $ Front Ratio:      % Back Ratio:      % Definitions Principle Balance: The initial amount the mortgage is taken out for. Down Payment: Amount of money that you pay off when you take out the mortgage. This amount gets deducted from the principle balance. Length of Mortgage: The number of years you have to pay the money back. Interest Rate: The cost of borrowing the money. Estimated Monthly Taxes: The amount you expect to pay for property taxes. Estimated Monthly Insurance:     The amount you expect to pay for insurance on the mortgage. Front Ratio: Ratio used to check your monthly mortgage payment including expected taxes and insurance against your monthly income. The standard ratio is 28%. Back Ratio: Ratio used to check your monthly expenses including your monthly mortgage payment against your monthly income. The standard ratio is 36%.