Blog · June 17, 2026

What the CRA wants in a mileage logbook

The full logbook, the simplified three-month sample, the 10-point rule with its formula, what each trip record needs, and how long to keep it.

The CRA does not prescribe a form for a mileage log. It prescribes what the log must show, and it offers one shortcut after you have kept a complete log for a full year. Here is the whole set of rules in plain terms, and the arithmetic behind the shortcut.

What every trip record needs

For each business trip, the CRA expects four things:

The date.
The destination.
The purpose (the client, the job, the reason for going).
The distance driven.

Personal trips do not need to be itemised, but the drive from home to a regular place of employment is one of them: it is commuting, and it is personal. Home to a point of call can be business. What matters is that the total business kilometres can be separated from the total kilometres the vehicle drove in the year, and that each business kilometre can be tied to a reason.

In practice, the destination and purpose are what an auditor reads. “Client meeting, 14 km” with no place is weak. “Dupont Plumbing, 2200 Sherbrooke East, estimate for kitchen reno, 14 km” is strong. If you use client or project tags, use them consistently so the reason for a trip is obvious without explanation.

Odometer at the start and end of the year

Alongside the trip records, the CRA wants the odometer reading at the beginning and at the end of each fiscal period. For most people that is January 1 and December 31. Those two readings give the total kilometres the vehicle travelled. Business kilometres divided by that total is the business-use percentage, and the percentage is what drives a T2125 deduction, or a line 22900 deduction for an employee with a T2200. Kilometres times the CRA allowance rate is not a deduction for either; it is an estimate of an employer allowance. The CRA also wants a separate record for each vehicle.

If you buy or sell a vehicle mid-year, record the odometer on the day of the change as well. The readings live with the log, not in a separate place where they get lost.

The full logbook

The default is a full logbook: every business trip, every day, for the whole year. The first year you claim vehicle expenses, this is required. It also becomes the base year for the shortcut below, so the more complete it is, the more useful it becomes later.

A full logbook does not require a particular medium. Paper, spreadsheet, or an app all work, provided the four fields are there and the records were made at or near the time of the trip.

The simplified logbook

After one full year, the CRA allows a three-month sample logbook in later years, under two conditions:

You kept a full logbook for a base year that is typical of your business use.
The three-month sample period in the current year shows business use within 10 percentage points of the same three months in the base year.

If both hold, you calculate the current year’s business use from the sample and the base year, and you do not need trip-by-trip records for the other nine months. You still need the odometer readings at the start and end of the year.

The 10-point rule and the formula

The formula is:

(sample period business use ÷ base year same-period business use) × base year annual business use = calculated annual business use

Then apply the check: the calculated annual figure must be within 10 percentage points of the base year’s annual figure. If it is not, the sample is not representative and a full log is needed for that year.

An example. In your base year (2025) you kept a full log. Business use for the whole year was 46%. For April to June of that year it was 51%.

In 2026 you keep a full log for April to June only. Business use for those three months is 55%.

Calculated 2026 business use: (55 ÷ 51) × 46 = 49.6%.

The check: 49.6% is within 10 points of 46%, so the sample stands, and 49.6% is your business-use percentage for 2026.

If the sample had come in at 70%, the calculation would give (70 ÷ 51) × 46 = 63.1%, which is more than 10 points above 46%. The shortcut fails, and you would need a full log for 2026.

Two cautions. The sample has to be three consecutive months. And the base year remains the reference for later years only as long as it stays representative; if your business changes, start a new base year.

Québec: the employer’s car

Québec asks for the same fields under section 41.1.5 of the Taxation Act (place of departure, destination, kilometres and proof of the work purpose for each trip, the days the car was available, and total kilometres), and adds one rule that applies only to an automobile the employer makes available to the employee. Under section 41.1.4 the employee hands the employer a copy of the logbook by the tenth day after the year ends, and section 1049.34 sets a $200 penalty for missing it. If you drive your own car, this rule does not apply to you.

How long to keep it

Keep the logbook, the odometer readings and the supporting receipts for six years from the end of the tax year they relate to. For a 2026 log, that means until the end of 2032. If you file late, the six years run from the date of filing. The CRA can ask for the records at any point in that window, and the log is what supports the number on the return.

Keeping a digital log for six years means keeping it in a format you can open in six years. A CSV or a PDF exported at year end is safer than relying on an app account still existing.

A checklist

Every business trip: date, destination, purpose, distance.
Odometer on January 1 and December 31 (or the vehicle change dates).
First year: a full log.
Later years: a full log, or a three-month sample that passes the 10-point check against a full base year.
Export at year end and keep for six years.

Where an app fits

An app that records trips by itself covers the date, distance and destination without you typing anything. The purpose still comes from you, one tap at a time, and the odometer readings still need to be entered. What the app adds is that the record is made at the time of the trip, which is exactly what the CRA means by a contemporaneous log.

Odie records the date, start and end points, route and distance of each trip, asks Work or Personal from the lock screen, accepts a client or project tag on work trips, stores dated odometer readings, and produces a year PDF and CSV with the trip log and the odometer bounds. The purpose of each trip is still your call.

Sources

Written by the Odie team. Not tax advice; your accountant knows your situation.