Business Mileage Log
What CRA expects in a mileage log, and the three-month sample rule.
The short version
- For every business trip, record the date, the destination, the purpose, and the kilometres. Also record the odometer at the start and end of the year.
- Your business-use percentage is business kilometres divided by total kilometres. Every vehicle deduction depends on it.
- After one full-year log, CRA accepts a three-month sample log in later years, as long as business use stays within 10% of the base year.
- A phone app or a paper book both work. A log rebuilt from memory in April usually doesn't survive a review.
- Keep the log for six years, like any other record.
CRA Mileage Log: What Records Do You Need?
CRA's auditors have read a lot of mileage logs written the night before the meeting. They can usually tell: same pen, same kilometres every Tuesday, no trips on the day the truck was in for brakes. The good news is that the requirement is modest, and a phone does most of the work now.
What a Log Must Show
| For each business trip | For the year |
|---|---|
| Date | Odometer reading at the start of the fiscal year |
| Destination (client, site, supplier) | Odometer reading at the end of the fiscal year |
| Purpose (meeting, delivery, estimate, pick up materials) | Odometer when you bought, sold or traded the vehicle, if during the year |
| Kilometres driven | Total business kilometres |
Example line: “Mar 14, 2026. Smith residence, 41 Main St, Collingwood. Site measure for estimate. 62 km.”
The Three-Month Sample Rule
Keeping a full log every year isn't required. CRA's simplified approach:
- Base year: keep a complete log for one full, typical 12-month year.
- Later years: keep a log for one continuous three-month period.
- Compare: if the sample's business-use percentage is within 10% of the base year, you can apply the base-year percentage (adjusted by the sample) to the whole year.
- If it isn't within 10%, the sample can't be used to extend the base year; you'll need a full log again.
A new truck, a new client mix or a move resets the picture; start a new base year.
Is your log good enough?
Describe how you track your driving and your business-use percentage. The assistant checks it against CRA's requirements and tells you what to fix before tax time.
Apps, Paper or a Spreadsheet?
All are acceptable if they record the required details. GPS apps that log trips automatically and let you tag each one as business or personal are the easiest to keep honest. Whatever you use, export or print it at year end and keep it with your receipts; see what records to keep and how long to keep them.
Common Logbook Mistakes
- Counting the drive from home to your shop as business.
- No odometer readings, so total kilometres are a guess.
- Round numbers on every trip.
- Claiming 100% business use on the only vehicle in the household.
- Logs that don't match fuel receipts or calendars.
What the log is used for is on vehicle expense deductions, claimed on line 9281 of the T2125 alongside your other business expenses. Employees claiming vehicle expenses need the same kind of log plus a T2200; see employment expenses.
CRA asked for your mileage log?
Upload the review letter. The Tax Document Analyzer explains what CRA wants, by when, and what to send to support your vehicle claim.
Mileage Log Questions
What does CRA require in a mileage log?
For each business trip: the date, destination, purpose and kilometres driven. For the year: odometer readings at the start and end, and total business kilometres.
Do I need to keep a mileage log every year?
After one full-year base log, you can keep a three-month sample log in later years, if business use stays within 10% of the base year.
Can I use an app for my CRA mileage log?
Yes. Any method that records the required details is acceptable. Keep an exported copy with your records.
What happens if I do not have a mileage log?
CRA can reduce or deny your vehicle expenses in a review, because the business-use percentage cannot be supported.
Sources: CRA, Motor vehicle expenses (logbook and simplified logbook); Guide T4002. Checked October 2026. How the sample-year percentage is applied is summarized; see CRA's page for the formula.
Last reviewed October 4, 2026 against CRA and Government of Canada sources. How we check our facts.