Mileage Tracking for Field Sales Reps: Records, Deductions & QuickBooks

Last updated: July 1, 2026

If you drive to customers for a living, your car is one of your biggest business expenses — and one of your biggest deductions, if you can prove it. This guide covers mileage tracking for sales reps who work for themselves: what a defensible log looks like, which miles count, and how to get the numbers into QuickBooks without a year-end scramble.

Why your records matter more than the math

The mileage deduction itself is simple: business miles multiplied by the IRS standard mileage rate (set each year — see the current rates on IRS.gov). What trips people up is substantiation. If your return is ever examined, the IRS doesn't take "I drive about 20,000 miles a year for work" — it expects records made at or near the time of the trips. A reconstructed log built from memory in April is exactly the kind of evidence that gets thrown out.

What a proper mileage log contains

For each business trip, your log should record:

• Date of the trip
• Destination — the customer, city, or address you drove to
• Business purpose — e.g. "sales call, Henderson Supply — quarterly review"
• Miles driven for that trip

On top of the per-trip entries, note your odometer reading at the start and end of the year so you can show total miles and the business-use percentage of the vehicle. Keep the supporting breadcrumbs too — calendar appointments, visit notes, customer records — since they corroborate that each trip really was business.

Business miles vs. commuting miles

Not every mile you drive for work is deductible. Commuting — driving from home to a regular office and back — is generally personal, even if you take sales calls the whole way. For a field rep, the miles that typically count are the ones between business stops: customer to customer, office to customer, customer to a supplier or the post office for business errands. If your home is your principal place of business (a real home office), trips from home to customers can generally count too. The rules have edges, so talk to your tax professional about your specific situation.

Standard mileage rate vs. actual expenses

You have two ways to deduct vehicle costs. The standard mileage rate is one flat per-mile figure that bundles gas, maintenance, depreciation, and insurance — simple, and usually the right call for an ordinary car with lots of business miles. The actual expense method instead deducts the business-use share of what the vehicle really cost you: fuel, repairs, insurance, depreciation. Actual expenses can come out ahead when the vehicle is expensive to run and your business mileage is relatively low. Two things to know: choosing actual expenses for a car in its first year of business use can lock you out of the standard rate for that car later, and either way you still need the mileage log to establish business-use percentage. Your tax professional can run both numbers for you.

Getting mileage into QuickBooks cleanly

The reps with the least tax-season pain treat mileage like any other transaction: record it as it happens, categorize it once, and let the books stay current. A workable routine looks like this:

1. Log each day's trips (date, destination, purpose, miles) the same day you drive them.
2. Convert miles to a dollar amount at your chosen rate.
3. Post it to a dedicated mileage or vehicle expense category in QuickBooks on a regular schedule — weekly beats quarterly.
4. Keep the trip-level log as your backup detail; QuickBooks holds the totals, the log holds the proof.

This is the part most reps automate. Because Terravai already knows the route you drove — it planned it — it calculates each day's mileage at your chosen rate automatically and exports it to QuickBooks Online as an expense in one tap, with the trip detail preserved behind it.

Make the log a byproduct of a well-planned day

Here's the quiet truth about mileage tracking for sales reps: the reps with the best logs are usually the ones with the best-planned routes, because the plan is the record. If every day starts from a stop list with addresses and purposes attached, your mileage log writes itself — and you drive fewer of those miles in the first place. If your days are still built ad hoc, start with our guide to planning a field sales route that hits more accounts in fewer miles.