The 28/36 Rule Here's another rule that is used by mortgage lenders - the "28/36 rule".  Your monthly household debt service should not exceed 28 percent of your gross monthly income. Your total debt service, including your house payments plus all other payments, should not exceed 36 percent of your gross monthly income. The percentages may be adjusted according to the costs of living and real estate prices of individual countries.   Back to Top | Next (More to think about)