Can I deduct business mileage if I forgot to track it?

Yes, you may still be able to deduct business mileage if you forgot to track it in real time — but only if you can reconstruct adequate records, and only if you’re otherwise eligible to deduct the mileage.

For U.S. taxes, self-employed people, independent contractors, and business owners can often deduct qualifying business vehicle use using either the standard mileage rate or the actual expense method. If you did not keep a contemporaneous mileage log, you should recreate one as accurately as possible using supporting evidence such as:

• calendar entries
• invoices or job/client records
• appointment logs
• emails or texts
• GPS or location history
• receipts
• bank or credit-card records
• route estimates from mapping apps

Your reconstructed log should ideally show, for each trip:

• date
• business purpose
• starting point and destination
• miles driven
• client, job, or business activity involved

Be careful: rough guesses with no backup are risky. Tax authorities generally expect substantiation, and business mileage rules are stricter than ordinary estimates. Also separate business miles from commuting and personal miles, because ordinary commuting is usually not deductible.

If you are a W-2 employee, be especially cautious. Unreimbursed employee business mileage has generally not been deductible on recent U.S. federal returns, though limited exceptions and state rules may apply, and 2026 rules should be checked against current IRS guidance.

Bottom line: if you’re self-employed or otherwise eligible, reconstruct a credible trip-by-trip log now and keep the backup documents. If you have no supporting records at all, the deduction may be difficult to defend.