Mortgage lenders are rejecting more applications this year, and it often has nothing to do with credit scores.
The number doing the damage is your debt-to-income ratio, or DTI—a simple calculation that compares what you owe each month to what you earn.
Add up your minimum monthly payments: car loan, student loans, credit cards, personal loans.
Divide that total by your gross monthly income before taxes.
A $1,500 debt load against $6,000 in monthly income equals a 25% ratio.
Most conventional lenders cap that number at 43%, though many now prefer 36% or lower.
Go above the threshold and you can be denied outright, even with an 800 credit score and a healthy down payment.
The math doesn't care how responsible you've been—it only cares about the ratio.
The squeeze is hitting buyers hard right now.
Average 30-year mortgage rates have hovered in the mid-6% range, and home prices remain near record highs in much of the country.
Higher rates mean higher monthly payments, which pushes DTI up before a buyer even adds existing debts to the equation.
A household earning $7,000 a month illustrates the problem.
A $350,000 mortgage at 6.5% runs roughly $2,212 a month for principal and interest, plus taxes and insurance.
Add a $450 car payment and $200 in credit card minimums, and the ratio lands near 41%—technically approvable, but with almost no cushion.
Lenders also weigh what's called the front-end ratio, which looks only at housing costs against income.
Keeping that under 28% is the traditional guideline, though some loan programs allow more.
FHA loans, for instance, can stretch to 43% or higher with compensating factors like cash reserves or a strong payment history.
If your ratio is too high, you have a few levers.
Paying down a credit card balance lowers the minimum payment and the ratio at the same time—often the fastest fix.
Paying off a small car loan entirely can wipe an entire line item from the calculation.
Increasing income helps too, though lenders typically want to see it documented for at least two years.
One trap to avoid: don't open new credit or finance furniture, appliances, or a car before closing.
Lenders often recheck your credit and debts just days before funding, and a new loan can blow up an approval that already cleared underwriting.
Self-employed buyers and gig workers face extra scrutiny.
Lenders average two years of tax returns, and write-offs that reduce taxable income also reduce the income figure used for DTI.
That's a legitimate tax strategy that can quietly wreck mortgage math.
The bottom line for anyone shopping this year: run your own numbers before a lender does.
Knowing your ratio early tells you whether to pay down debt first, save more, or shop in a lower price range.
Waiting until you've found the house is the expensive way to learn this lesson.
Our take: DTI is the most underrated number in personal finance, and most buyers only meet it at the worst possible moment.
Final Thoughts
Spend twenty minutes with a calculator and a bank statement before you tour a single home—it's the cheapest mortgage advice you'll ever get.