Business-Use Percentage
Quick definition
Business miles divided by total miles. Used to scale the actual-expenses deduction.
Business-use percentage is your annual business miles divided by your total annual miles. If you drove 30,000 miles total and 18,000 were business, your business-use percentage is 60%.
Where it applies
Business-use percentage is required for the actual expenses method. You add up your year's vehicle costs (gas, insurance, etc.) and multiply by the business-use percentage to get the deductible portion.
When it does not matter
Under the standard mileage rate, you only need to track BUSINESS miles plus year-end odometer readings. The total mileage figure is still required (Schedule C Part IV asks for it), but the math is per-business-mile, not per-business-percent.
Why total miles matter
Even if you use the standard rate, the IRS expects you to know your total annual miles to verify the business-use claim is plausible. A driver claiming 20,000 business miles on a vehicle that only put on 22,000 total would be claiming 91% business use, which is high for most self-employed people who also do personal driving.
Related terms
Actual Expenses Method
Deduct real vehicle costs times your business-use percentage, instead of using a flat per-mile rate.
Odometer Reading
Start-of-year and end-of-year vehicle odometer numbers. Required to verify total mileage on the tax return.
Standard Mileage Rate
The IRS-published per-mile deduction amount. 72.5 cents per business mile for 2026.
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