Simplified logbook calculator

After one full year of logbook, the CRA and Revenu Québec let you keep a logbook for a sample period of at least three months and project the year from it, if it stays close to the base year.

Base year: business use for the whole year (%)Base year: business use in the same months as the sample (%)This year: business use in the sample period, at least 3 consecutive months (%)

Try an official example: ·

Result

Calculated business use for this year: 54.3%

(51.0% ÷ 46.0%) × 49.0% = 54.33%

Sample period within 10 points of the base year's same months (36.0% to 56.0%)	✓ Yes
Calculated year within 10 points of the base year (39.0% to 59.0%)	✓ Yes

The 10% tolerance is applied as 10 percentage points.

The rule in short

Keep a full logbook for one 12-month base year.
In a later year, keep a logbook for a sample period of at least three consecutive months.
Calculated business use = (sample % ÷ base-year % for the same months) × base-year annual %.
The sample and the calculated year must each stay within 10 percentage points of the base year. If not, start a new full-year logbook.

Read more in the simplified logbook guide.

Keep the logbook on your phone

The iOS app records trips and odometer readings without GPS and without an account. It produces the T2125 and TP-80 vehicle figures from the same rules as these calculators. Your data stays on your phone.

Mileage Tracker & Log for CRA, coming to the App Store in Canada.

Official sources

Rules and amounts on this page were checked against these pages on 2026-10-16. This page is general information, not tax advice.