Debt-to-income ratio for a mortgage, explained with the math
A good credit score gets you through the door. Your debt-to-income ratio decides how big a loan you walk out with.
What DTI is
Your debt-to-income ratio is your total monthly debt payments divided by your gross (before-tax) monthly income. Lenders use it to judge whether you can carry a new mortgage payment on top of what you already owe.
Lenders usually look at two versions. The front-end ratio is just the new housing payment — principal, interest, property taxes, homeowners insurance, mortgage insurance and any HOA dues — divided by income. The back-end ratio adds every other monthly debt. The back-end number is the one that usually decides the application.
A worked example
Say you earn $7,000 a month before tax. You pay $450 on a car, $250 on student loans and a $60 minimum on a credit card: $760 a month in existing debt.
A home with a total housing payment of $2,100 a month gives a front-end ratio of $2,100 ÷ $7,000 = 30%, and a back-end ratio of ($2,100 + $760) ÷ $7,000 ≈ 41%.
Pay off the car before applying and the back-end ratio drops to about 34.4% — which can mean a larger loan, an easier approval, or both.
What counts as debt, and what does not
| Counted | Usually not counted |
|---|---|
| New mortgage payment, taxes, insurance, HOA dues | Utilities, phone, internet |
| Car loans and leases | Groceries, gas, childcare |
| Minimum credit card payments | Health and car insurance premiums |
| Student loans (even if deferred, under most program rules) | Subscriptions |
| Child support and alimony you pay | Rent you will stop paying when you move |
| Personal loans, other mortgages |
How high is too high
There is no single cap. A commonly cited benchmark is 43% back-end, which comes from the federal qualified-mortgage rules, but each program and lender sets its own limits and many approve higher ratios with compensating factors — strong credit, cash reserves, a larger down payment or a long job history. VA loans also weigh residual income: what is left each month after all obligations.
Being approved at a high ratio is not the same as being comfortable at it. The lender's ratio ignores childcare, saving for retirement and the repairs every house needs. Decide your own ceiling before the lender tells you theirs — how much house you can afford walks through that.
How to lower your DTI before you apply
- Pay off a small loan entirely — removing a whole monthly payment does more than paying down a big balance a little.
- Pay card balances down, which lowers minimum payments.
- Avoid any new financing — a car, furniture, a phone plan with a device loan — until after closing.
- Add a co-borrower whose income counts toward the application.
- Look at a lower price, a larger down payment, or a home with lower taxes and no HOA — each lowers the housing payment side.
- Consider homes with an assumable FHA or VA loan, where the payment may be well below a new loan's.
Income that is harder to count
Self-employed buyers usually need two years of tax returns, and lenders count income after business deductions — the write-offs that lowered your taxes also lower your qualifying income. Overtime, bonus and commission income generally needs a track record too. Talk to a lender early if your income is anything other than a steady salary.
Georgia costs that move the housing side of the ratio
The housing payment in your DTI is not just principal and interest, and in Georgia the extras vary a lot from one address to the next:
- Property taxes depend on the county, the city and the school district millage. Two similarly priced homes a few miles apart — say, either side of a county line — can carry very different tax bills. See property taxes in Georgia.
- Homestead exemptions lower the tax on a home you live in, but lenders usually qualify you on the current bill, which may not reflect your exemption yet.
- HOA dues count in full, and many newer metro Atlanta subdivisions have them.
- Homeowners insurance varies by the age of the roof, the location and your claims history; get a quote during due diligence so the lender's estimate is real.
Questions to ask your lender about DTI
Ask for the answers in writing, or at least in an email. Your agent can then filter homes by the real payment, not just the price — every listing on our home search shows an estimated monthly payment to start from.
- What back-end ratio does my file approve at, and what is the maximum for this program?
- Which of my debts are you counting, and at what monthly figure?
- If I pay off a specific account before closing, how much more can I borrow — and do I need to close the account?
- How are you counting my overtime, bonus, commission or self-employment income?
- What property tax and insurance figures are you using in the estimate?
Common questions
Is DTI based on gross or net income?
Gross — your income before taxes and deductions. That is one reason a lender's maximum can feel higher than what your take-home pay comfortably supports.
Do deferred student loans count toward DTI?
Usually yes. Most programs require the lender to count a payment for deferred loans, using either the actual payment on an income-driven plan or a calculated figure. Rules differ by loan type.
Does rent count in my debt-to-income ratio?
Not if you will stop paying it when you buy. The new mortgage payment replaces it in the calculation.
What is a good debt-to-income ratio?
Lower is better for both approval and comfort. 43% is a commonly quoted benchmark, but programs and lenders set their own limits, and many buyers feel more comfortable well below the maximum they are approved for.
Read next
General information for Georgia home buyers, not legal, tax or lending advice. Loan programs, rates, limits, tax rates and insurance terms are set by lenders, agencies, counties and insurers and change — confirm current figures with them, and have your closing attorney review anything you sign.