Mortgage lenders have a number they check before they ever look at your credit score in detail, and it catches a lot of buyers off guard.
It's called your debt-to-income ratio, or DTI, and it compares what you owe each month to what you earn.
Fall on the wrong side of the line, and a lender can turn you down even with a solid credit history and a healthy down payment saved up.
Add up your minimum monthly payments — car loan, student loans, credit cards, personal loans, plus the estimated new mortgage payment including taxes and insurance.
Divide that total by your gross monthly income, the amount before taxes come out.
If you bring in $6,000 a month and your total payments hit $2,400, your DTI is 40%.
Most conventional lenders prefer a DTI at or below 36%, though many will stretch to 43% or even 45% with compensating factors like cash reserves or a long work history.
FHA loans often allow DTIs up to 43% to 50% with strong credit, and VA loans can go higher still since the Department of Veterans Affairs doesn't set a hard cap.
The catch is that a higher ratio usually means a higher interest rate or extra requirements.
Here's the part that trips people up: lenders count the minimum payment on your credit cards, not what you actually pay.
If you charge $8,000 across three cards but the minimums total $240, that $240 is what lands in the calculation.
Paying a card off entirely removes that payment from the equation, which can drop your DTI by several points overnight and change what you qualify to borrow.
First, pay down revolving debt before you apply, since credit cards move the needle fastest.
Second, avoid financing a car or taking on new loans in the months before you shop for a mortgage — a new $450 payment can sink a deal that was already tight.
Lenders pull your credit and recheck your debts right before closing, so a furniture purchase on a store card during escrow can genuinely blow up the approval.
If your DTI is already too high, you have options beyond waiting.
A larger down payment lowers the loan amount and the monthly payment.
Adding a co-borrower with steady income raises the household earnings side of the fraction.
Some buyers also reduce their target price rather than their debt, which is the least painful path if you're flexible on the house itself.
One more wrinkle worth knowing: lenders calculate DTI using gross income, but you budget with take-home pay.
A 43% DTI can feel much tighter in real life once taxes, retirement contributions, and insurance come out.
Plenty of homeowners who technically qualified still feel stretched every month.
Our take: DTI is a useful gatekeeping number, but it's a lender's comfort zone, not a household's.
Before you let a pre-approval amount dictate your house hunt, run your own budget with actual take-home pay and see what payment you can live with.
Final Thoughts
The best mortgage is the one you can still afford in a month when the water heater dies.