Qualifying ratios compare proposed housing and total monthly debt obligations with accepted gross income.
Qualifying ratios are mortgage-underwriting percentages that compare the proposed housing expense and total counted monthly obligations with qualifying gross monthly income.
The plural label usually refers to two related tests: the housing-only Front-End Ratio and the total-debt Back-End Ratio. Together, they show whether pressure comes mainly from the proposed property or from housing plus the borrower’s other debts.
Qualifying ratios help organize an application, but they do not decide it alone. Credit, assets, reserves, LTV, property eligibility, loan type, underwriting method, and lender requirements also affect the result. The acceptable ratios are not universal across all mortgages.
During prequalification or preapproval, the lender estimates ratios from borrower-stated income, known debts, and a projected housing payment. During underwriting, those inputs are replaced with verified income, documented obligations, credit-report payments, and property-specific costs.
The ratios can be recalculated before closing if the rate, loan amount, taxes, insurance, dues, debts, or accepted income changes. A preapproval ratio is therefore a snapshot based on the assumptions available at that time.
Here, H is proposed housing expense, D is other counted monthly debt, and I is qualifying gross monthly income.
| Ratio | Numerator | Primary question |
|---|---|---|
| Front-end | Proposed housing expense | How large is the housing burden relative to income? |
| Back-end or total DTI | Housing expense plus other counted debts | How large is the total recurring debt burden relative to income? |
A borrower has $8,000 of qualifying gross monthly income, a $2,400 proposed housing expense, and $600 of other counted monthly debt.
The 7.5 percentage-point gap comes from non-housing debt. Paying off a counted obligation could reduce the back-end ratio without changing the front-end ratio, subject to the lender’s documentation and payment-treatment rules.
| Borrower-stated item | Underwriting question |
|---|---|
| Salary, bonus, overtime, or business income | What amount is documented, stable, and eligible as qualifying income? |
| Proposed mortgage payment | What payment must be used for the product and rate structure? |
| Taxes, insurance, and dues | What monthly property cost belongs in housing expense? |
| Credit-card balance | What required monthly payment must be counted? |
| Student loan | What payment calculation applies if the reported payment is deferred, missing, or income-driven? |
| Co-signed obligation | Is there enough evidence to exclude it under applicable rules? |
Debt-to-Income Ratio (DTI) commonly refers to the back-end or total-debt ratio. Qualifying ratios is the umbrella label for both housing-only and total-debt calculations.
Qualifying Income is the accepted income denominator. It is not itself a ratio.
Housing Expense is the dollar numerator used in the front-end ratio and part of the back-end numerator.
Residual Income is a dollar amount remaining after specified obligations rather than a percentage.
Loan-to-Value Ratio (LTV) measures property leverage. Qualifying ratios measure monthly payment pressure relative to income.