Mileage logbook rules for deduction
Depends. The exact requirements vary, but mileage deductions generally require a log that tracks business trips, separates business from personal use, and is kept consistently.
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On this page: Short answer · When it applies · When it doesn’t · Example · Records · Related · FAQ
Short answer
Depends. To support a mileage deduction, you typically need a mileage logbook (or equivalent records) that documents business trips and separates business from personal use.
A strong log is consistent, includes trip purpose, and is kept close to the time of the trips (not guessed at year-end).
When it’s more likely deductible
- You keep a log that records date, destination, business purpose, and distance/odometer readings
- You can clearly separate business vs personal trips
- You track totals for the period (e.g., monthly/yearly) and can summarize business-use percentage
- You keep supporting documents (calendar, invoices, job details) that align with trips
When it’s not deductible (or risky)
- You estimate mileage without a contemporaneous log or app records
- Your log is missing key details (no purpose, no destination, inconsistent dates)
- You claim commuting as business mileage
- You claim 100% business use when personal use is likely
Example
Example: what a single entry can look like
- Date: 2026-02-03
- Trip: Home → Client office → Home
- Business purpose: Project meeting
- Distance: 18 miles (or start/end odometer)
Repeat this consistently for business trips, then total business miles for the period.
What records to keep
- Mileage logbook entries (date, locations, purpose, distance/odometer)
- Start and end odometer readings for the year/period (if applicable)
- Supporting documents that match trips (appointments, invoices, job site info)
- If claiming vehicle expenses: receipts for gas/maintenance/insurance as applicable
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Tools that can help
Mileage tracking apps can automatically capture trips and generate logs/reports.
FAQ
What mileage logbook rules apply for a deduction?
In general, a mileage logbook should consistently record business trips with the date, destination, business purpose, and distance (or odometer readings), and allow you to separate business from personal use.
What should be included in a mileage log?
A mileage log typically includes the date, start and end location, business purpose, distance or odometer readings, and totals for the period.
Can I recreate a mileage log later from memory?
That can be risky. Recreated logs are harder to substantiate. It’s usually better to keep a contemporaneous log or use an app that records trips as they happen.
Looking for related deductible expenses? ← See Is mileage tax deductible?
Last reviewed: January 2026