Yes, buying a car will affect buying a house, and usually not in your favor. A new auto loan or lease adds a monthly payment to your debt-to-income ratio, a fresh hard inquiry and new account can shave points off your credit score, and the cash you put down on the vehicle is cash you no longer have for your mortgage down payment or reserves. The closer the car purchase falls to your mortgage closing, the more damage it can do.
How a Car Payment Shrinks the Mortgage You Qualify For
Mortgage lenders decide how much house you can afford largely through your debt-to-income ratio (DTI): your total recurring monthly debts, including the proposed mortgage payment, divided by your gross monthly income. A car payment lands squarely on the debt side.
As of the third quarter of 2025, the average monthly payment on a new-car loan was $748, and the average on a used-car loan was $532.1Experian. Average Car Payment For a borrower earning $7,000 a month, a $600 car payment eats up about 8.5% of gross income before any housing cost is counted.
Each mortgage program sets its own DTI ceiling:
- Conventional loans through Fannie Mae cap DTI at 45% for manually underwritten files, and up to 50% when approved through the automated underwriting system.2Fannie Mae. Debt-to-Income Ratios
- FHA loans use a 43% baseline, with room up to 50% for borrowers with strong credit and savings.
- VA loans use a 41% guideline but weigh residual income heavily, so a higher ratio isn’t automatically disqualifying.
Here’s how the math plays out. Say you earn $6,500 a month with $400 in existing recurring debts. At a 45% DTI limit, a lender allows total monthly debts of $2,925, leaving about $2,525 for a mortgage payment with taxes and insurance. Add a $650 car payment and your mortgage capacity falls to roughly $1,875. That gap can easily mean tens of thousands of dollars less in the home price you can afford.
What a New Auto Loan Does to Your Credit Score
Your credit score sets the interest rate a mortgage lender offers you, and a car purchase can move that score in two ways at once.
Applying for auto financing triggers a hard inquiry. FICO says a single hard inquiry lowers a score by five points or less. That’s small in isolation, but if your score sits near a pricing tier boundary, a few points can push you into a worse rate. FICO does group rate-shopping inquiries for the same type of loan: newer models use a 45-day window, older versions a 14-day window.3myFICO. The Timing of Hard Credit Inquiries: When and Why They Matter That grouping does not extend across loan types, so auto shopping and mortgage shopping are counted separately.
Opening the loan itself also lowers the average age of your accounts, a factor that makes up about 15% of your FICO score.4myFICO. How Are FICO Scores Calculated Borrowers with a thin file feel this more than those with a long credit history.
What does a lower score actually cost? Mortgage pricing is risk-based, so a 20-point drop can move you to the next tier up. On a $300,000 thirty-year mortgage, a rate half a percentage point higher adds roughly $90 to $120 a month and $32,000 to $43,000 in interest over the life of the loan.
The Hit to Your Down Payment and Reserves
A car purchase also drains the cash you need to close. Some conventional loans allow down payments as low as 3%,5Fannie Mae. HomeReady Mortgage and FHA loans require at least 3.5%.6Consumer Financial Protection Bureau. FHA Loans On a $350,000 home, that’s $10,500 to $12,250 at the low end. Spending $8,000 or $10,000 on a vehicle down payment can put those thresholds out of reach.
Lenders also look at reserves, the liquid funds left after closing. Fannie Mae doesn’t require reserves for most one-unit primary residence transactions, but a second home, multi-unit property, or cash-out refinance with a DTI above 45% requires two to six months of mortgage payments in reserve.7Fannie Mae. Minimum Reserve Requirements Even when reserves aren’t formally required, thin savings raise questions with underwriters.
Every large withdrawal from your bank account gets scrutinized. If $15,000 leaves your account for a car in the middle of the mortgage process, the lender will want a documented explanation, and the review may effectively start over.
Leases and Nearly Paid-Off Loans
Two common assumptions are worth correcting.
First, leases are not treated more gently than loans. Fannie Mae requires lease payments to be counted as recurring monthly debt regardless of how many months remain, because when a lease ends you’ll either sign another, buy out the vehicle, or get a different one.8Fannie Mae. B3-6-05, Monthly Debt Obligations A lease payment hits your DTI as hard as a loan payment of the same amount.
Second, an auto loan you’re almost done paying may not count. Fannie Mae lets lenders exclude an installment debt with ten or fewer monthly payments remaining, unless the remaining payments are large enough to affect your ability to cover the mortgage. And if a car loan is in your name but someone else actually makes the payments, that debt can be excluded from your DTI if you can provide 12 months of canceled checks or bank statements showing on-time payments from that person.8Fannie Mae. B3-6-05, Monthly Debt Obligations Without that paper trail, the full payment counts against you.
Why Timing Matters More Than People Expect
A pre-approval letter is a snapshot. Take on a car loan after receiving it and the letter no longer reflects your finances. The underwriter has to recalculate your DTI, confirm you still meet program guidelines, and reverify reserves. That can delay closing or, once you’re under contract, lead to denial.
The bigger risk comes at the end. Lenders run a final credit check, often called a credit refresh, in the days just before closing. Any new account, higher balance, or fresh inquiry shows up. If a new auto loan appears, the underwriter must recalculate DTI and reconfirm eligibility.9Fannie Mae. Undisclosed Liabilities Revised numbers that exceed your loan program’s limits mean the mortgage can’t be approved.
The safe rule is to avoid any new financing, including car loans, leases, and new credit cards, from the day you apply for the mortgage until the day the deed is recorded. If you truly need a vehicle in that window, paying cash from funds that aren’t part of your down payment or reserves is far less disruptive than taking on a loan.