DISCLAIMER:
This mileage log template is provided for informational and organizational purposes only. It is not intended to serve as legal, financial, or tax advice. Mileage rates and tax laws may change, and it is your responsibility to ensure accuracy and compliance. Always consult a qualified tax professional for advice specific to your situation. I make no guarantee as to the completeness or accuracy of this tool.
For 2025 standard mileage rates, see https://www.irs.gov/tax-professionals/standard-mileage-rates
One of the most commonly misunderstood tax deductions is the deduction for business use of a car. For small business owners, this is usually a personal car used for business purposes. The general instructions in this template, which are featured below, walk you through the framework of “business use of a car” deduction as discussed in Topic no. 510. The template also features a mileage log which can be used to keep detailed and accurate records to support any deduction you choose to take due to business use of a car. As always, consult a tax professional if you are unsure and do your own research!
The following text is from the template:
General Instructions:
As explained in Topic 510, Business Use of Car, there are two circumstances in which you can deduct the cost of using a car. The first is if you use a car exclusively for business purposes, in which case you may deduct the entire cost of owning and maintaining the car; however, you should consult Topic 704 and Publication 463 for further details on what may be deducted and in what amounts, as there are limitations.
The second case is if you use a car for a mix of business and personal use (Note: you may not deduct the cost of owning and maintaining a car that is not used for business purposes). Then, you have two options for figuring out the deductible amount for tax purposes. The first method is the standard mileage rate, which is the method assumed in this template. This is the simplest method; you simply track the total mileage used for business purposes and multiply it by a standard rate. For 2025, this rate is 70 cents per mile, but I have included other rates, such as for charity, medical, and military moving, if you want to use the template for individual tax return calculations as well. The conditions for using the standard mileage rate, according to Topic 510, are:
“To use the standard mileage rate, you must own or lease the car and:
You must not operate five or more cars at the same time, as in a fleet operation,
You must not have claimed a depreciation deduction for the car using any method other than straight-line,
You must not have claimed a Section 179 deduction on the car,
You must not have claimed the special depreciation allowance on the car, and
You must not have claimed actual expenses after 1997 for a car you lease.”
The second option, the actual expense method, is slightly more complicated as it attempts to pinpoint the true cost of the business use of your car. Topic 510 states:
“To use the actual expense method, you must determine what it actually costs to operate the car for the portion of the overall use of the car that’s business use. Include gas, oil, repairs, tires, insurance, registration fees, licenses, and depreciation (or lease payments) attributable to the portion of the total miles driven that are business miles.”
Please note that any tolls or parking fees incurred for business purposes are deductible regardless of which method you use, as they are not related to the operation and maintenance of the car itself!
Technically, it is best practice to calculate your deduction under both the standard mileage and actual expense method and choose the better (higher) deduction to lower your taxable income. However, many small business owners feel the difference is immaterial and therefore not worth calculating, which is why you will often hear small business owners opting for the standard mileage rate. Your tax professional can be of great use here!
Regardless of which method you choose, logging your mileage for business purposes will be extremely valuable for supporting your right to claim the deduction, and will provide you or your tax accountant more data to accurately calculate the amount of the deduction!
The Accounting Geek 
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