Car Loan Interest Deduction Calculator (Schedule C)
Calculate your allowable business vehicle interest deduction for self-employed individuals and 1099 contractors under IRC § 163(h)(2)(A) and IRS Publication 463.
Business Vehicle Parameters
Calculate your deductible interest based on annual loan payments and business mileage.
Is Car Loan Interest Tax Deductible?
For personal vehicles used purely for commuting and family transport, car loan interest has historically been non-deductible under the Tax Reform Act of 1986, codified in Internal Revenue Code Section 163(h)(1).
However, there are two important paths to deduct vehicle loan interest in 2026:
- Business Use on Schedule C (Line 16b): Self-employed individuals, independent contractors (1099), and sole proprietors can deduct the business portion of auto loan interest.
- Personal Auto Loan Disallowance (IRC § 163(h)(1)): Personal passenger vehicle financing interest is 100% non-deductible for W-2 wage earners on individual tax returns.
IRS Rules on Personal vs. Business Vehicle Loan Interest
Under Internal Revenue Code (IRC) § 163(h)(1), personal interest paid on consumer auto loans is strictly non-deductible for W-2 employees. However, self-employed taxpayers, sole proprietors, independent contractors, and LLC owners who use a financed vehicle for commercial purposes are permitted a direct tax deduction:
- Statutory Authority: IRC § 163(h)(2)(A) excludes trade or business interest from personal interest disallowance.
- Reporting Schedule: Claimed on IRS Schedule C (Form 1040), Line 16b (Interest: Other).
- Dual-Use Apportionment: If the vehicle is used for both commercial and personal driving, interest is deductible strictly in proportion to documented business mileage.
The Schedule C Business Mileage Method
When a vehicle is driven for both business tasks and personal use, self-employed taxpayers apportion loan interest based on documented mileage:
Deductible Percentage = Business Miles Driven ÷ Total Annual Miles Driven
For example, if you drove 20,000 total miles in 2026, and 14,000 of those miles were documented business trips (client visits, supply runs, site inspections), your business use ratio is 70%. If you paid $1,800 in auto loan interest over the year, you can deduct $1,260 on Schedule C.
Standard Mileage vs. Actual Expenses Rule
Unlike gasoline, oil changes, and auto insurance (which cannot be deducted if you choose the IRS standard mileage rate), business vehicle loan interest can be deducted alongside the standard mileage rate!
IRS Publication 463 explicitly confirms that self-employed taxpayers claiming the standard mileage deduction may still deduct the business portion of auto loan interest as a separate business expense on Schedule C.