In short: the deduction starts to shrink once your modified adjusted gross income (MAGI) rises above $100,000 for single filers or $200,000 for joint filers. Below those points you can deduct your full qualifying interest (up to the $10,000 cap); above them, the amount you can deduct gets smaller as your income climbs.
The income limit is the test that surprises people who assumed a US-made car was all it took. Assembly gets you in the door; your income decides how much of the interest actually survives.
MAGI, not just salary
The threshold is measured against modified adjusted gross income, not your gross salary. MAGI starts from your adjusted gross income and adds back certain items. For most households it's close to AGI, but if you have foreign income exclusions or other add-backs it can be higher than you'd guess. If you're anywhere near the thresholds, estimate carefully — a few thousand dollars of MAGI can change your result.
How the phase-out works
Think of it in three zones:
- Under the threshold ($100,000 single / $200,000 joint): your full qualifying interest is deductible, up to the $10,000 annual cap.
- In the phase-out range: the deductible amount is reduced as income rises above the threshold. The higher above the line you are, the less you can deduct.
- Far enough above: the deduction phases all the way down to nothing.
So two buyers with identical $6,000 interest bills and identical US-assembled cars can get very different results — one under the threshold deducts the full $6,000; one deep in the phase-out might deduct only part of it, or none.
Worked examples (plain English)
- Single filer, $80,000 MAGI, $5,000 interest: under the $100,000 line — the full $5,000 is deductible (within the $10,000 cap).
- Joint filers, $190,000 MAGI, $7,000 interest: under the $200,000 line — the full $7,000 is deductible.
- Single filer, well above $100,000 MAGI: in or past the phase-out — the deduction is reduced, and high enough it disappears.
Because the exact reduction depends on how far above the threshold you are, the reliable way to see your own number is to run the calculator with your MAGI and interest.
Ways the income limit changes your planning
If you're close to a threshold, the timing of income or the choice of filing status can matter. Married filing separately generally loses the $200,000 joint headroom. And remember this test is re-applied every year of the 2025–2028 window — a raise in a later year can shrink a deduction you got in full earlier.
Frequently asked questions
What is the income limit for the car loan interest deduction?
The phase-out begins above $100,000 modified AGI for single filers and $200,000 for joint filers. Below those points your full qualifying interest is deductible up to $10,000; above them it's progressively reduced.
Is the limit based on gross income or AGI?
It's based on modified adjusted gross income (MAGI), which starts from AGI with certain add-backs. For many people MAGI is close to AGI, but confirm yours if you're near the threshold.
If I'm over the limit, do I lose the whole deduction?
Not immediately. In the phase-out range the deduction is reduced, not zeroed. It only disappears once you're far enough above the threshold. Use the calculator to see where you land.
Does the income limit apply every year?
Yes. Each year of the 2025-2028 window is tested on that year's income, so a change in income can raise or lower your deduction from one year to the next.
This is general information, not tax advice. MAGI has specifics that depend on your full return - confirm yours with a tax professional if you're near the thresholds. Figures reflect the OBBBA car loan interest deduction for tax years 2025-2028.
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