How Much Is A 400 000 Mortgage How much do I need to earn a year to afford a $400,000. – Yep! You read that right. To carry a 30 year mortgage, on a $320,000 loan can cost you nearly a million dollars in potential wealth. How Much Do You Need to Make in Order to Afford a $400,000 Home. So far, everything written is to convince you why you can’t afford a $400,000 home if you can only afford the 30 year monthly payment.