Mortgage rates get all the headlines, but there's a less glamorous number that often decides whether you actually get the keys: your debt-to-income ratio.
Lenders call it DTI, and it's simply the share of your monthly gross income that goes toward debt payments.
If that number creeps too high, even a solid credit score and a fat down payment may not save your application.
Add up your minimum monthly payments on credit cards, car loans, student loans, and any personal loans, then add the mortgage payment you're hoping to take on, including taxes and insurance.
Divide that total by your gross monthly income.
If you earn $6,000 a month and your combined debt payments come to $2,400, your DTI is 40%.
Many conventional lenders prefer to see that number land at or below 43%, though some programs allow higher with compensating factors like cash reserves.
Lenders typically use the minimum payment listed on your credit report, not what you actually pay.
That $30 minimum on a $4,000 credit card balance still counts as $30, which sounds harmless until you stack several cards together.
Even borrowers on income-driven repayment plans may have their debt calculated at a percentage of the balance rather than the lower payment they actually make, which can push DTI up fast.
If your ratio is running hot, you have options.
Paying down revolving balances is the fastest lever because it lowers both the balance and the minimum payment.
Avoid financing a new car or furniture in the months before you apply, since a fresh installment loan can add hundreds to your monthly obligations.
Some buyers bring in a co-borrower with steady income, which raises the denominator and can drop DTI into a comfortable range overnight.
Self-employed borrowers and gig workers face extra scrutiny.
Lenders often average two years of tax returns, and aggressive write-offs that shrink your taxable income can make it harder to qualify for the loan you want.
If you're in that boat, it's worth talking to a loan officer well before you start house hunting so you know which numbers they'll actually use.
FHA loans generally allow DTIs up to around 43% to 50% with compensating factors, while VA loans can stretch higher for qualified veterans.
But a higher ratio usually means a tighter monthly budget long after closing.
A mortgage that technically qualifies can still leave you one car repair away from a credit card spiral. **The bottom line:** Your DTI is one of the few mortgage numbers you can meaningfully change before you apply, and doing so is often faster than waiting for rates to fall.
Pay down the cards, hold off on big purchases, and ask a lender to run your numbers early.
Final Thoughts
A little prep work now can save you from a rejection letter later.