Monthly nonmortgage debt repayments Debt payments-to-disposable income ratio Monthly disposable income You should strive to maintain a debt payments-to-disposable income ratio of 15% or less. Suppose that Brooke has a gross annual income of $55,000. Her annual deductions for taxes, 401(k) retirement plan contributions, and health insurance amount to $12,100. This leaves Brooke with an annual disposable income of $48,000. Dividing Brooke's annual disposable income by 12, you can determine that Brooke has a monthly disposable income of