Car loan interest is not deductible for personal vehicles, but it is deductible if you use the car for business
The short answer: if you borrowed money to buy a car you drive to work or for personal errands, you cannot deduct the interest you pay on your taxes. The IRS treats personal car loans the same way it treats credit card debt — the interest is straightforward a cost of borrowing money for yourself, not a business expense.
The exception is real and specific. If you use a vehicle primarily for business — meaning you drive it to meet clients, make deliveries, or perform work that is not commuting to an office — you can deduct a portion of the interest. The deduction is tied to the percentage of miles you drive for business versus personal use. A car that is 60% business use means you can deduct 60% of the interest paid that year.
This distinction matters because many people assume that because they use their car to get to work, the interest should be deductible. It does not work that way. Commuting to a job you work at — even if you are self-employed — is not considered business use by the IRS. Business use means the car itself is part of how you earn money.
Key Takeaways
- Interest on a car loan for personal use is never deductible, even if you drive the car to work.
- If you use a vehicle for business purposes, you can deduct the interest proportional to your business mileage percentage.
- You must track business miles separately from personal miles throughout the year to claim a deduction.
- Self-employed people and small business owners are most likely to benefit from this deduction, but only if the vehicle is genuinely used for business.
Who qualifies for a car loan interest deduction
The IRS allows a deduction only when the car is used in a trade or business. This includes self-employed people, freelancers, small business owners, and employees who use their own vehicle for work-related travel (not commuting). A real estate agent who drives clients to properties, a plumber who travels between job sites, or a consultant who meets clients at their offices all use their vehicles for business.
The vehicle must be used more than half the time for business purposes to may have access to at all. If you drive a car 40% for business and 60% for personal use, you cannot deduct any interest. Once you cross that 50% threshold, you can deduct interest only on the business-use portion.
Employees who drive their own cars for work-related travel (beyond commuting) may also deduct interest, but this is less common. If your employer requires you to use your personal vehicle and does not reimburse you, you may be able to deduct a portion of the interest, but you should verify this with a tax professional because the rules have changed in recent years.
How to calculate the deductible portion
The calculation is straightforward once you have your mileage records. Divide your business miles by your total miles driven in the year. That percentage is the portion of your interest that you can deduct.
For example: if you drove 12,000 business miles and 8,000 personal miles in a year (20,000 total), your business-use percentage is 60%. If you paid $2,000 in interest that year, you can deduct $1,200 (60% of $2,000).
You must keep a mileage log to support this calculation. The IRS does not require a specific format, but you need to record the date, destination, business purpose, and miles driven for each trip. Many people use a straightforward spreadsheet or a mileage-tracking app. At minimum, you should have contemporaneous notes — records made at or near the time you drove, not reconstructed months later from memory.
What documentation you need to claim the deduction
The IRS requires three pieces of documentation: proof of the loan and interest paid, a record of your business mileage, and evidence that the vehicle was used in business. Your lender will send you a Form 1098 or a statement showing interest paid during the year — keep this document.
Your mileage log is the most important piece. Without it, the IRS will not allow the deduction. The log does not have to be elaborate, but it must show business miles separately from personal miles. A straightforward spreadsheet with date, destination, purpose, and miles is sufficient. Some people photograph their odometer at the start and end of the year, then keep a running log of business trips.
You should also keep records showing the vehicle's business purpose. This might be a contract with a client, invoices showing you traveled to meet them, or a job description stating you use your vehicle for work. The more documentation you have, the stronger your position if the IRS questions the deduction.
How the deduction appears on your tax return
If you are self-employed, you report the deduction on Schedule C (Profit or Loss from Business). The interest goes in the "Interest" line item, but only the business-use portion. You do not deduct the full amount and then reduce it — you calculate the business percentage first, then enter only that amount.
If you are an employee using your own vehicle for work, the deduction rules changed significantly in 2017. Currently, employee business expenses — including vehicle interest — are not deductible for most people. This rule applies unless you are a member of the military reserves, a fee-basis government official, or a performing artist. If you fall into one of these categories, you can deduct the business-use portion of your interest on Form 2106.
The safest approach is to work with a tax professional or use tax software that walks you through the business-use calculation. You will need your mileage log and your loan statement ready when you prepare your return.
The difference between deducting interest and using the standard mileage rate
You have two ways to deduct vehicle expenses: the actual expense method or the standard mileage rate. You cannot use both in the same year, and the choice affects how you handle interest.
With the actual expense method, you deduct real costs: interest, insurance, fuel, maintenance, depreciation, and registration. You calculate the business percentage and deduct that portion of each expense. This method works well if you have high interest payments or significant maintenance costs.
With the standard mileage rate, you multiply your business miles by a fixed rate per mile (set by the IRS each year). This rate is meant to cover all vehicle expenses, including interest. If you use the standard mileage rate, you do not separately deduct interest — it is already factored into the per-mile amount. You can only deduct interest separately if you use the actual expense method.
Most people find the standard mileage rate simpler because it requires only a mileage log, not detailed expense records. However, if your car has a high interest rate or you financed a large amount, the actual expense method might yield a larger deduction. A tax professional can calculate both scenarios for you.
Common mistakes to avoid
The most common mistake is claiming a deduction for commuting. Driving to your office or job site is not business use, even if you are self-employed. The IRS is clear on this: commuting is a personal expense, not a business expense. Only miles driven for work-related purposes beyond getting to your workplace count.
Another mistake is not keeping a mileage log. Without contemporaneous records, the IRS will disallow the entire deduction if you are audited. A log created months after the fact, or one that estimates miles, carries little weight. Start tracking on January 1 and keep records throughout the year.
A third mistake is mixing personal and business use without clearly separating them. If you drive the same car for both purposes, you must track which miles are which. A car that is 100% personal use one year and 70% business use the next year is fine — the deduction applies only to the year you actually used it for business.
Frequently Asked Questions
Can I deduct car loan interest if I use my car to commute to work?
No. The IRS does not consider commuting a business use, even if you are self-employed or drive a long distance. Only miles driven for work-related purposes beyond getting to your workplace — such as meeting clients, making deliveries, or traveling between job sites — count as business use.
What if I use the same car for both business and personal driving?
You can deduct the interest proportional to your business mileage. If you drive the car 60% for business and 40% for personal use, you deduct 60% of the interest paid. You must keep a detailed mileage log separating business and personal miles to support this calculation.
Do I need to report the vehicle to the IRS when I claim the deduction?
You do not need to register the vehicle with the IRS, but you must document its business use. Keep your mileage log, loan statements, and any records showing the vehicle was used for business purposes. If audited, you will need to show this documentation.
Can I deduct interest on a car I financed for my business if I am a corporation?
Yes. If your business entity (corporation, LLC, or partnership) owns the vehicle and uses it for business, the interest is a deductible business expense. The vehicle must be titled in the business name, and you must track business versus personal use if the vehicle is used for both.
What happens if my business use drops below 50% during the year?
You lose the deduction entirely for that year. The IRS requires more than 50% business use to deduct any interest. If you start the year at 60% business use but drop to 45% by year-end, you cannot deduct any interest for that tax year. Track your mileage carefully to stay above the threshold.