What is Debt-to-Income Ratio?
Your debt-to-income (DTI) ratio is the percentage of your gross monthly income that goes towards debt repayments. It is one of the most important metrics lenders use when assessing mortgage applications, personal loans, and other forms of credit.
Front-End vs Back-End DTI
Lenders typically calculate two DTI ratios:
- Front-end DTI (housing ratio): Total housing costs (mortgage principal, interest, property taxes, insurance) ÷ gross monthly income. UK lenders focus on this for affordability assessments.
- Back-end DTI (total debt ratio): All monthly debt payments (housing + loans + credit cards + BNPL + student loans) ÷ gross monthly income. This is the more comprehensive figure.
DTI Thresholds by Lender Type
- UK mortgage lenders: Generally require total committed monthly expenditure to be below 40–45% of net income (stress-tested at higher rates).
- US conventional mortgages: Back-end DTI typically capped at 43–50%.
- Australian lenders (APRA stress tests): Assessed at rates 3% above the loan rate; total debt service below 35–40% of gross income is preferred.
How to Improve Your DTI
- Pay down high-balance debts before applying for a mortgage.
- Avoid taking on new credit (car finance, BNPL, credit cards) in the months before applying.
- Increase gross income through a second income, pay rise, or renegotiation.
- Close unused revolving credit lines — lenders sometimes count the potential debt, not the current balance.