Acceptable — front-end 24%, $2,100 debt ÷ $5,000 income
DTI is the share of your gross (pre-tax) monthly income that goes to monthly debt obligations, expressed as a percentage. Mortgage lenders compute it both ways: front-end (housing only) and back-end (housing plus all other monthly debts). Lower is better — the lower your DTI, the more headroom you have in your budget for a new loan payment.
DTI = (Total Monthly Debts / Gross Monthly Income) × 100
Debt-to-income ratio measures monthly debt obligations against gross monthly income. Lenders use it as a coarse-but-effective filter for borrower risk: a borrower whose monthly debts already eat 50% of their pre-tax income has very little cushion if their car breaks down or interest rates rise. Two flavors matter. Front-end DTI counts only housing costs (mortgage principal and interest, property taxes, homeowners insurance, HOA dues, and PMI if applicable) — the conservative guideline is ≤28%. Back-end DTI adds every other monthly debt: car loans, credit-card minimum payments, student loans, child support, alimony — the conventional-loan threshold is ≤36%, and the Qualified Mortgage (QM) rule caps back-end DTI at 43% for most loans. Income is gross monthly (before tax and benefit withholding), not net take-home — this is one of the most common DTI mistakes.
A buyer has a $1,200 mortgage payment, a $300 auto loan, $200 in credit-card minimums, and a $400 student loan — $2,100 in total monthly debts. Their gross monthly income is $7,000. Compute their front-end and back-end DTI.
If the back-end DTI were 38% instead, the borrower would still qualify under the QM 43% ceiling but might face a higher interest rate, mandatory reserves, or a larger required down payment from conventional lenders who prefer the 36% threshold.
Three distinctions trip people up most often. First, gross vs net income — DTI always uses gross monthly income (before tax, benefit, or retirement withholding), never take-home pay. Using net income inflates your apparent DTI by 20–30% and can disqualify you from a loan you'd actually be approved for. Second, what counts as debt — lenders count anything that shows up on your credit report as a fixed monthly obligation: mortgage, rent, auto loans, student loans, credit-card minimum payments (not the full balance), personal loans, child support, alimony, and any court-ordered judgments. Lenders do not count utilities, groceries, insurance not bundled into your mortgage, subscriptions, or one-time expenses. Third, the 28/36/43 hierarchy — these aren't all the same rule. 28% is the conservative front-end (housing-only) ceiling; 36% is the conventional back-end target; 43% is the federal Qualified Mortgage hard limit that prevents the loan from being classified as a riskier non-QM product. FHA loans sometimes accept back-end DTI up to 50% with compensating factors.
Debt-to-income (DTI) ratio is the percentage of your gross monthly income that goes to monthly debt obligations. Mortgage lenders compute it both as a front-end ratio (housing costs only) and a back-end ratio (housing plus all other monthly debts). It's the single most-used affordability metric in mortgage underwriting because it captures cash-flow stress without requiring a full credit profile.
Divide your total monthly debt payments by your gross monthly income, then multiply by 100. For example, $1,800 in monthly debt against $5,000 of gross monthly income gives DTI = ($1,800 / $5,000) × 100 = 36%. Always use gross (pre-tax) income, not net take-home pay, and include every fixed monthly obligation that appears on your credit report.
Most lenders consider DTI under 36% as good — comfortable cash flow with room for a new payment. Under 28% is excellent. 36-43% is acceptable but may come with higher interest rates or stricter conditions. Above 43% is high and disqualifies the loan from Qualified Mortgage status, meaning the borrower will likely need a non-QM lender or have to pay down debt first.
The federal Qualified Mortgage (QM) rule caps back-end DTI at 43% for most conventional and government-backed loans. FHA loans sometimes accept up to 50% with compensating factors like a large down payment, significant cash reserves, or excellent credit. VA loans don't have a strict DTI ceiling but lenders typically prefer back-end DTI under 41%.
Front-end DTI counts only housing costs — mortgage principal and interest, property taxes, homeowners insurance, HOA dues, and PMI. The conservative guideline is ≤28%. Back-end DTI adds all other monthly debts (car loans, credit-card minimums, student loans, child support, alimony) and is what the 36% conventional and 43% QM thresholds apply to. Lenders look at both numbers.
DTI itself does not directly affect your credit score — credit bureaus don't see your income. However, the credit-utilization ratio (credit-card balances ÷ total credit limits) is one of the largest credit-score factors, and high utilization usually correlates with higher DTI. Indirectly, a lower DTI suggests you're managing balances well, which tends to support a better credit score.
There are two levers: lower the numerator (monthly debts) or raise the denominator (gross monthly income). Pay down the highest-balance revolving debt first to shrink minimum payments, refinance high-rate loans to lower monthly payments, avoid taking on new debt before a mortgage application, and document any side income (rental, freelance) on tax returns so it counts toward gross income.
Mortgages or rent, property taxes and homeowners insurance, HOA dues, auto loans and leases, student loan minimum payments, personal loans, credit-card minimum payments (not the full balance), child support and alimony, and any court-ordered judgments. Utilities, groceries, gas, subscriptions, and discretionary spending are not counted.
Reference: Consumer Financial Protection Bureau, Ability-to-Repay/Qualified Mortgage Rule (12 CFR §1026.43). Fannie Mae Selling Guide B3-6-02, Debt-to-Income Ratios.
Debt-to-income ratio is the share of gross monthly income consumed by monthly debt obligations:
Where:
Mortgage lenders look at both ratios. Front-end DTI flags borrowers who are stretching for a house they can't carry; back-end DTI flags borrowers whose total debt load already crowds out a new payment. Both numbers must stay under the lender's threshold for a clean, best-rate approval.
First-Time Buyer
A buyer has a $1,400 proposed mortgage payment, a $250 auto loan, $150 in credit-card minimums, and a $300 student loan. Gross monthly income is $6,000.
Back-end DTI = 35% (under both 36% and 43% caps).
This profile qualifies cleanly for a conventional loan with best-tier pricing. The 23.3% front-end DTI is also well under the 28% conservative guideline.
Refinance Check
Current monthly debts (excluding the proposed new mortgage) are $800. Gross monthly income is $7,500. The new mortgage payment would be $1,800.
Back-end DTI ≈ 34.7% — just inside the 36% conventional cap.
The refinance is approvable at conventional terms, but very little headroom. Adding another $100/month of debt would push back-end DTI over 36% and into the higher-rate tier.
High-DTI Borrower
A borrower has $2,400 in monthly debts (including the proposed mortgage) and $4,800 of gross monthly income.
Back-end DTI = 50% — above the QM threshold.
FHA loans occasionally accept up to 50% with strong compensating factors (large down payment, six months of reserves, excellent credit). VA loans don't have a strict DTI ceiling but typically prefer back-end DTI under 41%.
| DTI Range | Tier | Typical Lender View |
|---|---|---|
| ≤ 28% | Excellent | Top-tier pricing. Comfortably under front-end and back-end guidelines. |
| 28% – 36% | Good | Conventional approval, typically clean pricing on prime credit. |
| 36% – 43% | Acceptable | Inside QM ceiling but may face rate add-ons or required reserves. |
| > 43% | High | Above QM. Need non-QM, FHA with compensating factors, or VA. |
Tiers apply to back-end DTI. Front-end DTI uses the more conservative 28% guideline. FHA and VA loans use their own program-specific overlays.
