If you use a financed vehicle for work, the car loan interest tax deduction for business use can put real money back in your pocket. Self-employed individuals, freelancers, and small business owners who drive for business are eligible to write off the interest portion of their car payments — but only when they follow the right method and keep proper records.
This guide explains how the business interest deduction works under the actual expense method, how it interacts with the standard mileage rate, and what you need to know about the new personal-use car loan interest deduction signed into law in 2025.
How the Car Loan Interest Tax Deduction Works for Business
When you finance a vehicle and use it for business, the IRS lets you deduct the interest paid on your auto loan as part of your vehicle expenses. This deduction is available through the actual expense method and is reported on Schedule C (or Schedule F for farmers).
The key factor is your business use percentage. If you drive 15,000 miles in a year and 9,000 of those miles are for business, your business use percentage is 60%. You can then deduct 60% of your total car loan interest for the year.
What Counts as Business Use
Business miles include driving to meet clients, traveling between job sites, making deliveries, and running business errands. Your daily commute from home to a fixed office does not count. If you work from a home office, however, trips from home to business destinations are generally deductible.
For more detail on what qualifies, see our guide on vehicle expense deductions for the self-employed.
Actual Expense Method: Deducting Car Loan Interest
Under the actual expense method, you add up every cost of operating your vehicle and multiply the total by your business use percentage. Car loan interest is one of several deductible expenses under this method:
- Loan interest
- Gas and oil
- Insurance premiums
- Repairs and maintenance
- Registration fees
- Depreciation
For example, suppose you paid $3,600 in loan interest during the year and your business use percentage is 70%. Your deductible interest would be $2,520. That amount, combined with the business portion of your other vehicle costs, goes on Schedule C.
Keep in mind that only the interest portion of your monthly payment is deductible — the principal repayment is not, because you recover the vehicle cost through depreciation instead.
For a side-by-side comparison of both IRS methods, see standard mileage rate vs actual expenses.
Standard Mileage Rate: Interest Is Deductible on Top
If you are self-employed and use the standard mileage rate, you can still deduct the business portion of car loan interest separately. Per IRS Publication 463, interest on a car loan, parking fees, tolls, and personal property taxes on the vehicle are all deductible on top of the standard mileage rate for Schedule C filers.
For example, if you drive 15,000 business miles and paid $3,000 in loan interest with a 70% business use percentage, you would claim 15,000 x $0.725 = $10,875 in mileage plus $2,100 in interest. Note that W-2 employees cannot deduct car loan interest separately under the standard mileage rate — this benefit applies only to self-employed taxpayers.
The standard mileage rate is simpler and still works well for drivers with lower operating costs. With the ability to add interest on top, it can also be competitive for self-employed drivers with financed vehicles.
You must choose the standard mileage rate in the first year you place a vehicle in service for business. After that first year, you can switch between methods from year to year.
Self-Employment Tax Benefit
When you deduct car loan interest (or any vehicle expense) on Schedule C, it does more than reduce your income tax. It also reduces your self-employment tax. The SE tax is calculated on 92.35% of your net self-employment income, so every dollar of vehicle deductions lowers both income tax and SE tax.
If your combined federal and SE tax rate is around 40%, a $2,500 interest deduction could save you roughly $1,000 in total taxes.
The New OBBBA Car Loan Interest Deduction (Personal Use Only)
The One Big Beautiful Bill Act (OBBBA), signed into law on July 4, 2025, created a new above-the-line deduction for car loan interest. Here are the key details:
- Maximum deduction: $10,000 per year
- Effective dates: 2025 through 2028
- Eligibility: Available to both standard deduction and itemizer filers
- Vehicle requirement: Must be a new vehicle with final assembly in the United States, and original use must begin with the taxpayer
- Income phaseout: Begins at $100,000 MAGI ($200,000 for joint filers) and fully phases out at $150,000 ($250,000 joint)
This deduction is for personal-use vehicles only. If you already deduct car loan interest as a business expense on Schedule C, you cannot claim the OBBBA deduction for the same interest. The two deductions cannot overlap.
However, if you own two vehicles — one for business and one for personal use — you could deduct interest on the business vehicle through the actual expense method and claim the OBBBA deduction on the personal vehicle, as long as both meet their respective requirements.
Starting with the 2026 tax year, lenders will issue Form 1098-VLI to report qualifying interest paid.
Record-Keeping Requirements
The IRS requires substantiation for any car loan interest deduction. To stay audit-ready:
- Track every business mile — record the date, destination, business purpose, and odometer readings for each trip
- Save loan statements — keep monthly statements or year-end summaries showing how much interest you paid
- Calculate your business use percentage — total business miles divided by total miles driven
- Separate personal and business interest — if claiming the OBBBA deduction on a different vehicle, keep records for both
A mileage tracking app eliminates most of the guesswork. Tripbook logs each trip with GPS coordinates, timestamps, and purpose notes — exactly what the IRS expects in an audit.
Which Method Should You Choose?
| Factor | Standard Mileage Rate | Actual Expenses |
|---|---|---|
| Car loan interest | Deductible on top of the rate (self-employed) | Deducted separately |
| 2026 rate | 72.5 cents per mile | N/A |
| Best for | Older vehicles, low costs | Newer financed vehicles |
| Record-keeping | Miles only | Miles + all expense receipts |
If your monthly car payment includes significant interest and your business use percentage is high, the actual expense method almost always wins. Run the numbers both ways before filing.
For a deeper look at insurance-specific deductions under actual expenses, see car insurance tax deduction for the self-employed.
Common Mistakes to Avoid
- Deducting principal payments — Only interest is deductible, never the principal portion of your loan payment
- Double-dipping on interest — You cannot deduct interest on Schedule C and also claim the OBBBA deduction for the same vehicle
- Forgetting the business use percentage — You must prorate every expense by business miles, not total miles
- No mileage log — Without a contemporaneous log, the IRS can disallow your entire vehicle deduction
Start Tracking Your Business Miles
Whether you choose the standard mileage rate or the actual expense method, accurate mileage records are the foundation of every vehicle tax deduction. The car loan interest tax deduction for business use requires a clear, IRS-compliant log proving what percentage of your driving is work-related.
Download Tripbook to automatically track every business mile and generate the reports you need at tax time.
