IRS Finalizes Car Loan Interest Deduction Rules (T.D. 10054): 9 Things Now Official

1. The exact phase-out math is now law

This is the biggest news for anyone near the income limits. The final regulations lock in the formula the IRS floated in December 2025: your $10,000 cap shrinks by $200 for every $1,000 (or fraction of $1,000) your modified adjusted gross income sits above the threshold.

The IRS's own example: a single filer with $124,200 MAGI has $24,200 of excess, which rounds up to 25 steps — a $5,000 reduction, leaving $5,000 deductible. Full phase-out hits at $150,000 MAGI for single filers ($250,000 for joint filers). Our calculator now uses this exact formula.

2. $10,000 per return — married filing separately each get $10,000

The final rules confirm the $10,000 limit applies per federal tax return, not per vehicle or per person. Two car loans on a joint return still share one $10,000 cap. But married couples filing separately each get their own $10,000 cap on their respective returns.

3. Leases are out — definitively

No ambiguity left: interest-like charges on a leased vehicle do not qualify, even when the lease agreement uses the word 'interest.' You must have purchased the vehicle with a loan.

4. Negative equity rolled into the loan doesn't count

About 30% of new-car purchases in 2026 involved negative equity from a trade-in. The final rules say debt tied to that rolled-over balance is not treated as debt incurred to buy the new vehicle — so interest on that portion is not deductible. Only the portion financing the new car itself qualifies.

5. More than just stated interest can qualify

The IRS confirmed that 'qualified' interest goes beyond the interest rate on your contract. Points, deferred and capitalized interest, certain origination and financing charges, prepayment penalties, and even late-payment or default charges can qualify — as long as they're treated as interest for federal tax purposes.

The same goes for costs customarily financed with the purchase: extended warranties, service contracts, GAP coverage, credit insurance, title and registration fees, and dealer-installed accessories.

6. Lenders must report on new Form 1098-VLI

Starting with 2026 loans, any lender (or other interest recipient) that receives $600 or more of annual interest on a qualifying vehicle loan must report it on new Form 1098-VLI, including the borrower's information, interest received, outstanding principal, loan origination date, vehicle year/make/model, and — critically — the VIN. Returns missing the VIN are at high risk of disallowance.

7. Refinancing keeps status only up to the old balance

Refinancing a qualifying loan doesn't kill the deduction — but it doesn't expand it either. Only the outstanding balance of the original loan keeps qualifying status; any new money added at refinance does not. And adding a co-borrower at refinance does not make the new borrower eligible.

8. Personal use is tested when you buy, not every year

The vehicle must be for more than 50% personal use — but the test happens at loan origination. If you reasonably expected personal use above 50% when you bought the car, later changes generally don't retroactively disqualify you. The business-use portion of interest keeps its old treatment and is not subject to the $10,000 cap.

9. First-lien rule gets practical relief

Qualifying loans must be secured by a first lien, but the IRS clarified you don't lose the deduction over paperwork timing: delayed lien perfection, temporary involuntary liens under state law, repossession (while you remain liable), and total-loss claims where the insurer releases the lien all keep the loan qualifying.

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