Most homebuyers obsess over their credit score and forget the one figure that can sink a loan application faster: debt-to-income ratio.
It's a simple division problem, but it decides whether you get approved, how much house you can afford, and what interest rate you'll be offered.
Add up every monthly debt payment — car loan, student loans, minimum credit card payments, personal loans, and any new mortgage payment you're applying for.
Divide that total by your gross monthly income (what you earn before taxes).
The result is your DTI, expressed as a percentage.
Under that, you're in conventional loan territory.
Above it, many banks won't touch you, and the ones that will often charge more.
Some government-backed loans, like FHA mortgages, allow DTIs up to around 50% with compensating factors, but that's a tighter squeeze than most budgets can handle.
Say you earn $6,000 a month before taxes.
A $400 car payment, $250 in student loans, and $150 in credit card minimums already eat $800.
That leaves $1,780 for a mortgage if you're aiming for a 43% cap — roughly a $200,000 loan at today's rates.
What trips people up is the credit card minimum.
Lenders don't look at what you actually pay each month; they look at the minimum due on your statement.
Paying $500 toward a card doesn't help your DTI if the minimum says $35.
The fix is paying balances down or off before applying, which lowers the reported minimum.
If you co-signed a car loan for a family member, that payment counts against you even if they've never missed a payment.
Lenders see the obligation, not the arrangement.
Self-employed buyers face a different headache.
Lenders typically average two years of tax returns, and every deduction you took to lower your tax bill also lowered your qualifying income.
That can push an otherwise reasonable DTI over the limit.
The practical move is to run your own numbers before a lender does.
Pull your credit report, list every minimum payment, and divide by your gross monthly pay.
If you're near 40% or higher, focus on eliminating a payment entirely rather than shaving a few dollars.
Paying off a $250 monthly loan does more for your DTI than a small raise.
Renters hoping to buy should also remember that rising rents don't count against DTI, but they do drain the savings needed for a down payment and closing costs.
Both problems compete for the same dollars.
The bottom line: your DTI is a snapshot, and snapshots can be improved with a few months of focused payoff.
Check it early, fix what you can, and shop at least three lenders — they don't all use the same cutoff.
Final Thoughts
A slightly lower ratio can mean thousands saved over the life of a loan.