Vehicle Logbook Requirements for Ontario Business Owners: What the CRA Expects as Proof

If you drive for work — visiting clients, picking up supplies, moving between job sites — you can generally deduct the business-use portion of your vehicle expenses. The catch is proving what that portion actually is. Without a proper vehicle logbook, a vehicle expense claim is one of the first things a CRA reviewer questions, because the business-use percentage is entirely self-reported until you're asked to back it up.

A logbook doesn't need to be fancy. It needs to be contemporaneous, complete, and consistent — three things that a lot of after-the-fact reconstructions simply aren't. This guide sets out what CRA expects a compliant log to contain, how the simplified method works once you've established a baseline, and where business owners most often go wrong.

Why a Logbook Matters More Than the Receipts

Fuel, insurance, lease or loan payments, maintenance, and parking receipts prove what a vehicle cost. They say nothing about how much of that cost relates to business use versus personal driving. The logbook is what connects the two — it's the evidence that turns a pile of receipts into a defensible percentage.

Without one, a reviewer has no way to accept your claimed percentage other than taking your word for it, which is exactly the position you don't want to be in if your file gets a closer look.

What a Compliant Logbook Records

At minimum, a usable log tracks each trip with enough detail to reconstruct the business purpose later:

A log that's filled in weeks later from memory, or that simply states a round total at year-end, carries far less weight than one built trip-by-trip as the year goes on.

The Two Ways to Track Business Use

Full-Year Logbook

Recording every trip for the entire year is the most thorough approach and the easiest to defend, but also the most tedious to maintain long-term.

The Simplified (Sampling) Method

Once you've kept a full 12-month logbook in a base year, CRA administrative guidance allows many businesses to switch to a shorter sample logbook in later years — typically a continuous few-month period — and use it to project a business-use percentage for the full year, provided your driving pattern hasn't changed significantly. This administrative approach can reduce the ongoing burden, but the underlying condition — a genuine base-year log, followed by a representative sample — still has to be met. Confirm the current version of this guidance before relying on it, since CRA's administrative positions can be updated.

Common Logbook Mistakes

• Reconstructing the log at tax time. A calendar of client meetings can help you rebuild trips, but a log created entirely after the fact is weaker evidence than one kept as you go.
• Recording only a lump total. A single stated business-use percentage with no trip-level detail behind it gives a reviewer nothing to verify.
• Mixing personal errands into a "business" trip without separating them. A client visit that's followed by a personal stop should reflect only the business-related distance.
• Letting the log go stale after the base year. If your route, client base, or work pattern changes materially, an old sample no longer supports this year's percentage.
• No odometer readings at all. Trip-level detail without a start and end reading for the year makes the overall percentage hard to verify.

A Quick Checklist Before You Claim

• [ ] Log has a date, destination, purpose, and distance for each business trip
• [ ] Odometer readings recorded at the start and end of the year
• [ ] Personal and business kilometres are clearly separated, not blended
• [ ] Log was kept as trips happened, not reconstructed at filing time
• [ ] If using the simplified method, the original base-year log is still on file
• [ ] Receipts for fuel, insurance, maintenance, and lease/loan payments are kept alongside the log

Frequently asked questions