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Schedule C
Schedule C

Schedule CProfit or Loss From Business (Sole Proprietorship)

46 — Written Evidence to Support Deduction Updated for tax year 2025

Does this apply to you?

  • You claim car and truck expenses on line 9
  • You complete Part IV for your business vehicle
  • You keep (or should keep) a mileage log or similar record

Easy to overlook

“Written evidence” means a contemporaneous log A mileage log created at the time of each trip satisfies the requirement. A summary reconstructed at year-end from memory or calendar entries does not. The IRS specifically looks for records made at or near the time of the expense. Digital mileage tracking apps that log trips automatically are the most reliable form of evidence. 1 IRS Publication 463 — Travel, Gift, and Car Expenses

Answering “no” is an audit invitation While the IRS does not automatically disallow your deduction for answering “no,” this answer tells them your documentation is weak. If your return is selected for examination, vehicle expenses without written evidence are among the easiest deductions for the IRS to deny completely. 2 Audit pattern — vehicle expense deductions without mileage logs

Watch out for this

Answering “yes” without actually having adequate records. If you answer “yes” and are audited, the IRS will ask to see the log. Claiming you have written evidence when your only record is a year-end estimate undermines your credibility and can lead to penalties for negligence on top of losing the deduction.

Footnotes

  1. IRS Publication 463, Travel, Gift, and Car Expenses. https://www.irs.gov/pub/irs-pdf/p463.pdf

  2. IRS Publication 463, Travel, Gift, and Car Expenses, Recordkeeping. https://www.irs.gov/pub/irs-pdf/p463.pdf

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