DTI: why they approve you for less house than you expected
It happens constantly: someone saved well, has the cash to close, and the bank approves far less than expected. The savings are rarely the problem. It is DTI, and it is the piece that moves fastest.
What it is, with an example
DTI is the share of your gross monthly income already going to debt, counting the new mortgage. The ceiling reaches 50%: it is the maximum allowed by Fannie Mae automated underwriting on a conventional loan.
On $6,000 a month, 50% is $3,000. Inside that has to fit the car, the cards, student loans and the full house payment: mortgage, taxes, insurance, mortgage insurance if the down payment is small, and association fees if it is a condo.
| Item | Monthly |
|---|---|
| Gross income | $6,000 |
| 50% ceiling | $3,000 |
| Car | $500 |
| Cards (minimums) | $250 |
| Left for the house | $2,250 |
Why it hurts more than it looks
In that example, the car and the cards ate $750 of capacity. That is not $750 of house: it is tens of thousands of dollars of maximum price, because every monthly dollar compounds across thirty years of loan.
The math that surprises people
A $500 monthly car payment can be costing you up to about $77,000 of house you could otherwise reach: that is what $500 a month finances over thirty years at the average fixed rate today, 6.71% (Freddie Mac, September 2026). And since inside DTI those $500 also carry taxes and insurance, in practice the figure comes out lower.
So when someone is close but not there, the first thing I look at is not how much more they can save. It is which debt they can get off their back.
What actually lowers it
- Closing one small debt completely beats paying a little toward several. DTI counts the monthly payment, not the balance: a debt paid off disappears from the calculation entirely.
- The car is usually the biggest lever of all, especially if only a few payments remain. One caveat: that holds for a financed car. If it is a lease, the payment counts in full no matter how close the end of the contract is.
- Opening nothing new while you are buying. Financing furniture before closing has killed closings that were already approved.
- Documentable income. What cannot be proven on paper does not count, even if it comes in every month.
The advantage of DTI over savings is speed: raising available cash takes months. Getting a payment off your back can change your number in weeks.
The 50% is the maximum allowed by Fannie Mae automated underwriting on a conventional loan, and it is the outer edge, not a permission: many paths cap lower. Manually underwritten conventional stops at 45%, and manual FHA at 43% without compensating factors. Each lender also applies its own rules when calculating income and debt.
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If you want the number for your situation instead of the example, Umbralio works it out in under two minutes. No credit pull, no Social Security number.
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