Debt-to-Income ratio is the percentage of your gross monthly income that goes toward debt payments, used by lenders, mortgage underwriters, and refinance approvers to evaluate your creditworthiness.
What it means in plain English
DTI is calculated by dividing your total monthly debt payments by your gross monthly income. Lenders generally prefer total DTI below 43% for mortgages, with even lower thresholds (around 36%) for the most competitive rates.
For NPs entering practice, student loan payments are the largest single line item in DTI. On a $115,000 income, the standard 10-year payment on $150,000 of debt would push DTI to 18% from the loan alone, before any housing or auto debt.
Switching to SAVE or another IDR plan dramatically lowers your reported DTI because mortgage underwriters typically use your actual IDR payment rather than a hypothetical higher amount.
Why it matters for NP students
DTI is the gating metric for mortgage approval. An NP carrying $150,000 of student debt on the standard plan has a much harder time qualifying for a $400,000 mortgage than the same NP on SAVE with a $665 monthly payment.
DTI also matters for refinancing student loans, the lowest advertised refinance rates require DTI below ~30% in most lenders' models.
Cosigning a parent's loan or a sibling's car can spike your DTI even if you don't pay the bill. Lenders see the full payment as your obligation regardless of who actually pays.
How it actually works
The math behind Debt-to-Income Ratio is more concrete than most borrowers realize. Here's a worked example using current 2026 numbers.
Common pitfalls
- Using your standard payment for mortgage applications when you're actually on SAVE.
- Forgetting cosigned debt counts in your DTI.
- Including credit card minimums but not full balances, underwriters use minimum payments, but high utilization separately hurts your credit score.
- Assuming income from per diem or moonlighting work counts, most underwriters require two years of history.
- Not running the DTI math before house shopping, then having loan refusals derail timing.
Related terms
Helpful tools
Run the numbers on your specific situation with these calculators and matching tools.