You've got a shoebox full of Esso and Petro-Canada receipts. You figure CRA sees $7,200 in gas = business use. Wrong.
Gas receipts prove you bought fuel. They don't prove where you drove, why, or whether it was business mileage. When CRA audits your vehicle expenses, they want a contemporaneous mileage log — and if you don't have one, they'll disallow up to 73% of your claimed mileage deduction.
Here's what most contractors get wrong about mileage tracking in Canada — and how much it's costing you.
Let's say you drove 38,000 km last year. Mix of job sites, supplier runs, client meetings. You claimed $0.70/km (CRA's 2026 rate for Ontario, first 5,000 km) = $26,600 in mileage deductions.
CRA audits you. You hand them a stack of gas receipts.
They ask: "Where did you drive on March 12th? What was the business purpose? How many kilometers?"
You don't have a log.
CRA's standard disallowance: They'll accept maybe 10,000 km (generous estimate for "reasonable business use" based on your invoices). The rest? Gone. You just lost $19,600 in deductions. At a 31% marginal tax rate (Ontario), that's $6,076 in extra tax — plus interest and potential penalties.
Real CRA Audit Case (Ontario Electrician, 2024): Claimed 42,000 km business use. Had gas receipts, no log. CRA allowed 12,000 km. $21,000 in disallowed deductions = $7,140 tax hit. Took 14 months to settle.
CRA's mileage log requirements:
Gas receipts tell you when you filled up and how much you spent. They don't answer any of CRA's questions.
CRA does allow a simplified logbook method: keep a full log for a representative 12-week period (one base year + same period each year after). If your business use percentage stays consistent, you can apply that ratio to future years.
The catch: You still need a complete log for those 90 days — and if your driving pattern changes (new territory, more quotes, different suppliers), CRA can reject it. Most contractors' driving is too seasonal (winter shutdowns, summer surges, festival work) for this to hold up.
Ask any electrician, plumber, or framer why they don't log mileage. You'll hear:
The real cost: If you drive 35,000 business km/year and don't track it, you're leaving $24,500 in deductions on the table — or risking $6,000+ in audit penalties if you guess.
February rolls around. You realize you have zero mileage records. You open Google Calendar, pull up job addresses from QuickBooks, and build a log that says:
"Jan 15 — Kanata site visit (45 km), Jan 17 — RONA run (22 km), Jan 19 — client quote Stittsville (38 km)..."
Looks legit, right?
CRA's position: This is a reconstructed log, not a contemporaneous record. You're estimating distances (Google Maps doesn't know you stopped at two other sites). You're guessing dates based on invoices (what about the quote you didn't win? The callback that didn't get billed?).
In an audit, CRA will:
If they catch you reconstructing, they disallow the whole claim.
CRA doesn't care how you track mileage — paper, app, or spreadsheet — as long as it's contemporaneous and complete.
Pros: No battery, no app to forget. Physical evidence CRA trusts.
Cons: Easy to lose, hard to read your own handwriting in March, no automatic calculations.
Verdict: Works if you're disciplined. Most contractors aren't.
Pros: Auto-detect trips via GPS, categorize business vs. personal, export CRA-compliant reports.
Cons: You have to remember to review/classify trips. Subscription cost ($60-$120/year). Battery drain.
Verdict: Good if you're phone-disciplined and don't mind the monthly fee.
Text yourself after each trip: "Kanata job site, 45 km" or "RONA Barrhaven, 18 km, grabbed wire for Henderson reno."
End of week: forward the thread to your ops inbox. AI extracts:
Pros: No app, no paper, no "remember to start the tracker." Just text like you already do.
Cons: Requires a system that processes the texts (that's what we built).
Verdict: Best for contractors who won't use apps but will text.
Let's run the numbers for an Ontario-based electrician:
Without a mileage log:
Cost to track properly: ~2 minutes per day (text your trips) = ~12 hours/year. Even at $50/hour (your billable rate), that's $600 in time.
Net gain: $6,442 - $600 = $5,842/year.
Or pay someone to do it for you (Truck Cab Ops = $79/week = $4,108/year) and still net $2,334 while getting your evenings back.
CRA audits are rare (3-5% of self-employed filers), but vehicle expenses are a red flag category. If your mileage claim is >50% of vehicle costs, or you're claiming >40,000 km/year, you're more likely to get reviewed.
The audit process:
Timeline: 8-18 months. Stress level: High.
You can't fix January-March, but you can start April 2 (today) and still save thousands this year.
Step 1: Record your odometer reading
Take a photo of your odometer right now. That's your baseline. (CRA wants total annual km — business + personal.)
Step 2: Pick a method
Paper log in the truck, MileIQ app, or text-yourself system. Doesn't matter which — just pick one and stick with it.
Step 3: Log EVERY trip
Job site, supplier run, quote, client meeting, even "drove to Kanata to pick up a tool I forgot." If the truck moved for business, it counts.
Step 4: End-of-week review
5 minutes every Sunday: total your km, flag missing entries, clean up messy notes. (Or forward your texts to Truck Cab Ops and we do this.)
Step 5: Year-end odometer
Dec 31: photo of odometer again. Total km driven = business km (from log) + personal km (the difference).
That's it. Do this for 9 months (Apr-Dec) and you'll still save ~$4,800 this year.
Gas receipts won't save you from a CRA mileage audit. You need a contemporaneous log — and if you don't have one, you're risking $4,000-$7,000 in disallowed deductions every year.
Tracking mileage takes 2 minutes a day. Not tracking it costs you $6,000/year in lost deductions — or more if CRA comes knocking.
Your truck is already your office. Make it work for you at tax time.
Text your trips. We'll track, categorize, and build your CRA-compliant mileage log every week — along with receipts, invoices, and everything else buried in your inbox.
$39 first week. $79/week after. Try it risk-free.
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