How Big of a Mortgage Can I Afford? Not only does owning a home give you a haven for yourself and your family, it makes great financial sense, too. This calculation assumes a 28 percent income tax bracket. If your bracket is higher, your savings will be too. Rent: _________________________ Multiplier: X 1.32 Mortgage payment:__________________ Because of tax deductions, you can make a mortgage payment—including taxes and insurance—that is approximately one-third larger than your current rent payment and end up with the same amount of income. For more help, use the Fannie Mae’s online mortgage calculators. Copyright 2007.  Realtor Magazine Online.