Is there a simplified way to keep a mileage log for my vehicle that the CRA accepts?

Yes. The CRA accepts a "simplified logbook" method for taxpayers who have established their vehicle's business-use percentage in a full base-year logbook. Once you have a complete 12-month logbook for a base year, you can maintain a three-month sample logbook in subsequent years to verify that your business-use percentage has not changed significantly compared to the base year.

To use this method, the vehicle must be used in the same or similar way year over year. If your use changes materially — for example, you significantly expand your business or stop using the vehicle for client visits — a full-year log is required again for that year to establish a new base.

The three-month sample should be a representative period, not necessarily a specific quarter. The CRA expects you to retain both the base-year logbook and all annual sample logs as supporting documentation. This simplified approach is convenient but not risk-free: if your claimed percentage looks inconsistent with your actual business activities, the CRA may probe further. Keeping the base-year logbook indefinitely (not just for six years) is good practice given that it anchors all subsequent reduced-form records.