CRA mileage log: what your logbook must include in 2026
If you are self-employed in Canada and use your own car for work, you can deduct part of what the car costs you: fuel, insurance, repairs, licence and registration, lease payments or loan interest, and capital cost allowance. The CRA lets you deduct only the business share of those costs, and the logbook is how you prove what that share is.
For every business drive, the CRA asks you to record:
1. the date 2. the destination 3. the purpose 4. the number of kilometres
Once a year: the odometer reading at the start and at the end of your fiscal period, and the total kilometres you drove.
Keep it for six years.
Why the logbook decides your deduction
The CRA works out the deductible amount by comparing business kilometres with all the kilometres you drove. Its own example: Murray drove 27,000 km for business out of 30,000 km in total, and his truck cost $7,000 to run that year.
(27,000 ÷ 30,000) × $7,000 = $6,300
Without a log, the business kilometres are just a guess, and a guess is the first thing that falls apart if the CRA asks questions. With a log, every kilometre in that fraction is backed by a dated entry.
What a good entry looks like
| Date | Destination | Purpose | km |
|---|---|---|---|
| Mar 4 | 1200 Centre St, client office | Quote for kitchen renovation | 18.4 |
| Mar 4 | Home Depot, Shepard | Materials for the Smith job | 9.7 |
An illustrative example, not real data.
"Business" on its own is not a purpose. Write what the trip was for: a client, a job, a supplier, a meeting.
The two odometer readings most people forget
Besides the trips, the CRA wants the odometer reading of each vehicle at the start and at the end of the fiscal period. For most sole proprietors that is January 1 and December 31. The difference is your total kilometres, the bottom half of the fraction above. Take a photo of the dashboard on both days; it takes ten seconds and settles the total.
The simplified logbook: three months instead of twelve
Keeping a log all year, every year, is tedious, and the CRA offers a shortcut. You keep a full logbook for one complete year, the base year. In later years you can keep a log for a three-month sample period and scale it up:
(sample period % ÷ base year same period %) × base year annual % = business use this year
The CRA's example: in the base year the full log showed 49% business use for the year and 46% for April to June. In a later year, April to June showed 51%. So (51% ÷ 46%) × 49% = 54%.
The result is accepted only if it stays within 10% of the base year, which here means between 39% and 59%. If your work changes and the number moves further than that, the base year no longer reflects how you use the car and you should start a new 12-month base year.
The full base-year logbook has to be kept for six years from the end of the last tax year you use it for.
Receipts are part of the record
The logbook proves the business share; receipts prove the costs. The CRA allows motor vehicle expenses only when they are reasonable and supported by receipts. Fuel, repairs, insurance and parking all count, and parking for business is deductible in full rather than by percentage.
Common mistakes
- Rebuilding the year in April. A log written from memory months later is hard to defend. Record trips as they happen, or at least weekly.
- No purpose. Date, place and kilometres without a reason do not show that the trip was for business.
- No odometer readings. Without them the total kilometres, and therefore the percentage, are unsupported.
- Mixing vehicles. Keep a separate log for each vehicle you use for work.
Sources
Rocmile notices when you drive, records the route and builds the logbook: date, destination, purpose and distance for every business drive. Swipe right for business, left for personal. No account, no servers: your drives stay on your iPhone. Free.