Yes, it is called a debt-to-income ratio. Depending on what type of mortgae you get it can range from 28% to 50% depending on loan underwriting requirements. They will also look at your other debts in calculating what you can afford. The lower the debt to income ratio, the better chance you have of getting a lower interest rate. For example let's say you put 20% down a house, you have decent credit, and you borrow $300,000 for a traditional 30 yr fixed. Your payments would be around $1,750 at 7% interest rate. If you made $100,000 a year you would have a debt-to-income ratio of 21% if you made $50,000.00 you would have debt-to-income of 41%. You can go as high as 50% but you will pay a higher interest rate. I do not think there any loan programs that go above 50%.