The Car Loan Interest Deduction: What Section 163(h)(4) Actually Requires
The car loan interest deduction lets an individual deduct up to $10,000 a year of interest on a loan used to buy a qualifying passenger vehicle for personal use, for taxable years 2025 through 2028, whether or not the client itemizes. Section 70203 of the One Big Beautiful Bill Act (Public Law 119-21) created it by adding paragraph (4) to IRC Section 163(h). The headline fits on a dealer's banner. Underneath it sit a vehicle test, a loan test, a VIN requirement, and a phaseout that starts at $100,000 of MAGI ($200,000 joint).
Most of the questions I expect on extended 2025 returns and on 2026 planning come from a client who bought the right car with the wrong loan, or the wrong car with the right loan.
Key Takeaways: The Car Loan Interest Deduction Under Section 163(h)(4)
- Up to $10,000 of interest per taxable year, for taxable years beginning after December 31, 2024, and before January 1, 2029.
- Claimed on Schedule 1-A, Part IV, whether the client itemizes or not. It is not a Section 62 deduction.
- The debt must be incurred after December 31, 2024, for the purchase, and secured by a first lien. Leases never qualify.
- Original use must commence with the taxpayer, GVWR under 14,000 pounds, final assembly in the United States.
- The capped amount shrinks by $200 per $1,000 (or portion) of MAGI over $100,000, or $200,000 joint. The cap does not double.
- No VIN on the return, no deduction.
What Is the Car Loan Interest Deduction?
The car loan interest deduction is a temporary exception to the personal interest disallowance in Section 163(h), so interest on a qualifying vehicle loan becomes deductible for 2025 through 2028. The operative sentence in Section 163(h)(4)(A) reads:
"In the case of taxable years beginning after December 31, 2024, and before January 1, 2029, for purposes of this subsection the term personal interest shall not include qualified passenger vehicle loan interest."
Placement on the return is where preparers slip. Section 70203(b), under the heading "Deduction allowed to non-itemizers," added paragraph (7) to Section 63(b): "so much of the deduction allowed by Section 163(a) as is attributable to the exception under Section 163(h)(4)(A)." Nothing in Section 70203 amends Section 62. It follows the same Section 63(b) route OBBBA used for the overtime deduction under Section 225, and it sits on the same new schedule.
The IRS fact sheet FS-2026-04 states that "Eligible taxpayers can claim the deductions on this schedule whether they itemize deductions or claim the standard deduction." Car loan interest is Part IV, MAGI is computed in Part I, and the Part VI total goes "on the Form 1040, line 13b."
Which Vehicles Qualify?
A vehicle qualifies only if it passes all six tests in Section 163(h)(4)(D) and its final assembly occurred in the United States. The vehicle must be one:
- "the original use of which commences with the taxpayer,"
- manufactured primarily for use on public streets, roads, and highways (not a vehicle operated exclusively on rails),
- with at least 2 wheels,
- that is a car, minivan, van, sport utility vehicle, pickup truck, or motorcycle,
- treated as a motor vehicle for purposes of title II of the Clean Air Act, and
- with a gross vehicle weight rating of less than 14,000 pounds.
The statute does not use a new-versus-used label. The test is original use, and that is why the typical used car fails: somebody else's original use already happened. Frame the client conversation that way, because the statute does.
Assembly is a separate exclusion. The term "shall not include any vehicle the final assembly of which did not occur within the United States," and Section 163(h)(4)(E)(i) defines final assembly as "the process by which a manufacturer produces a vehicle at, or through the use of, a plant, factory, or other place from which the vehicle is delivered to a dealer with all component parts necessary for the mechanical operation of the vehicle included with the vehicle, whether or not the component parts are permanently installed in or on the vehicle."
The VIN-on-the-return rule and the assembly test are separate requirements, but the IRS lets the same VIN support the assembly test too. Fact sheet FS-2025-03 says the final assembly location "will be listed on the vehicle information label attached to each vehicle on a dealer's premises," and that "taxpayers may rely on the vehicle's plant of manufacture as reported in the vehicle identification number (VIN)." The NHTSA VIN Decoder website provides that plant information. Keep the label or the decoder result in the file.
How Do the Loan Requirements Work?
The debt must be incurred by the taxpayer after December 31, 2024, for the purchase of the vehicle, secured by a first lien on it, with the vehicle bought for personal use. Section 163(h)(4)(B)(i) covers interest "on indebtedness incurred by the taxpayer after December 31, 2024, for the purchase of, and that is secured by a first lien on, an applicable passenger vehicle for personal use." Section 70203(e) matches: the amendments "apply to indebtedness incurred after December 31, 2024." A 2024 purchase loan fails, no matter when the interest is paid.
Section 163(h)(4)(B)(ii) excludes five kinds of debt outright: a loan to finance fleet sales, a loan for a commercial vehicle not used for personal purposes, any lease financing, a loan for a vehicle with a salvage title, and a loan for a vehicle intended for scrap or parts.
Refinancing counts, within limits. Section 163(h)(4)(E)(ii) includes debt from refinancing qualifying debt, secured by a first lien on the same vehicle, "but only to the extent the amount of such resulting indebtedness does not exceed the amount of such refinanced indebtedness." In an illustrative case, a client who refinances a $32,000 balance into a $38,000 cash-out loan has $32,000 of qualifying debt. The rule also reaches only refinancing of "any indebtedness described in such subparagraph," meaning debt that already qualified. I would not read it to bring a 2024 purchase loan into the deduction by refinancing it later.
Related-party debt is out. Section 163(h)(4)(E)(iii) excludes "any indebtedness owed to a person who is related (within the meaning of Section 267(b) or 707(b)(1)) to the taxpayer." When the note holder is not a commercial lender, run the relationship through both sections.
The VIN is a condition, not a formality. Under Section 163(h)(4)(B)(iii), interest does not qualify "unless the taxpayer includes the vehicle identification number of the applicable passenger vehicle [...] on the return of tax for the taxable year." Two vehicles means two VINs.
How Do the $10,000 Cap and the MAGI Phaseout Work?
The deduction is capped at $10,000 of interest per taxable year, and the capped amount is then reduced by $200 for each $1,000, or portion of $1,000, by which MAGI exceeds $100,000 ($200,000 on a joint return). The reduction applies to the amount "determined without regard to this clause and after the application of clause (i)," so the order is cap first, then phaseout. MAGI is AGI increased by amounts excluded under Section 911, 931, or 933.
The joint return doubles the threshold, not the cap. The phaseout has a joint-return figure. The $10,000 cap has none, and it applies to total qualifying interest for the year, not per vehicle. A couple with two qualifying loans shares one ceiling.
The full $10,000 is gone at $150,000 of MAGI for a single filer, $250,000 joint. $10,000 divided by $200 is 50 steps, and 50 steps of $1,000 is $50,000 over the threshold. Because "or portion thereof" rounds each partial step up, $1 over the threshold already costs $200, and a single filer with any MAGI above $149,000 has already reached the 50th step.
Less interest phases out sooner. The reduction runs against the interest the client actually has.
Two illustrative computations, with numbers of my own:
| Joint return, two vehicles | Single filer, one vehicle | |
|---|---|---|
| Qualifying interest paid | $12,400 | $4,300 |
| After $10,000 cap | $10,000 | $4,300 |
| MAGI | $213,500 | $118,200 |
| Excess over threshold | $13,500 | $18,200 |
| Steps of $1,000 or portion | 14 | 19 |
| Reduction at $200 per step | $2,800 | $3,800 |
| Deduction | $7,200 | $500 |
The single filer loses everything once MAGI passes $121,000, since 22 steps ($4,400) exceed the $4,300 of interest.
What Will the Lender Report Under Section 6050AA?
Any person in a trade or business that, in the course of that business, receives $600 or more of interest from an individual in a calendar year on a specified passenger vehicle loan must file an information return at the time the Secretary provides, and give the borrower a statement by January 31 of the following year. Section 70203(c) added Section 6050AA. The return is "in such form as the Secretary may prescribe" and shows the borrower's name and address, the interest received for the year, the outstanding principal at the beginning of the year, the origination date, and the year, make, model, and VIN of the vehicle (or another description the Secretary prescribes), plus any other information the Secretary requires.
The borrower statement adds the lender's information contact and repeats the interest, principal, origination date, and vehicle items. It "shall be furnished on or before January 31 of the year following the calendar year." Both the return and the statement were added to the Section 6724(d) penalty definitions.
Two practical reads. The statement will usually put the interest, the origination date, and the VIN in one place, which is most of what Part IV needs. For 2025, FS-2025-03 says "The IRS will provide transition relief for tax year 2025 for interest recipients subject to the new reporting requirements," so do not assume a standard statement arrives. The lender's year-end loan statement may be what you have. The Section 6050AA statement itself does not certify that the vehicle passed the original-use, weight, or assembly tests. And $600 is a reporting threshold only. Section 163(h)(4) has no minimum, so a client under $600 still has a deduction and may simply get no statement.
Before You Prepare Part IV
Build the intake around the tests: loan origination date, lien position, personal use, original use, GVWR, assembly location, a VIN for each vehicle, and any refinancing history. Then apply the cap and the phaseout in that order. The window closes with taxable years beginning before January 1, 2029, so this is four filing seasons of the same checklist.
When a file raises a question the statute does not answer on its face, I start in Tax Orator with the Section 70203 text and the fact sheet side by side.