What Counts as Business Mileage? IRS Rules with 8 Examples

Most mileage disputes are not about distance. The odometer is rarely in question; the reason for the drive is. Business mileage is defined by purpose, and purpose is the part of the record people forget to write down.

This guide sets out the test the IRS applies, walks eight everyday drives through it, and covers the edge cases that quietly fail — the errand chained onto a client visit, the stop on the way home, the second office.

The two-part test

A drive is business mileage when both of the following hold:

1. It is ordinary and necessary for your trade or business. Ordinary means common and accepted in your line of work. Necessary means helpful and appropriate — not indispensable, which is a lower bar than it sounds.
2. It is not personal commuting. Travel between your home and your regular place of work is a personal expense, no matter how far it is or how early you leave.

Both parts have to be satisfied. The first is usually easy; the second is where most miles are won or lost, because commuting has a specific meaning that does not match the everyday one.

Publication 463 is the source document for both parts, and it is worth reading the transportation chapter once if mileage is a material part of your return.

Eight drives, sorted

#	The drive	Business mileage?	Why
1	Home → your regular office	No	Ordinary commuting, regardless of distance
2	Office → client site → office	Yes	Travel between work locations during the business day
3	Home office → client site	Yes	With a qualifying home office, the first stop is not a commute
4	Home → temporary work site (under a year)	Yes	Temporary locations are treated differently from regular ones
5	Client site → second client site	Yes	Both ends are business locations
6	Office → bank to deposit business takings	Yes	Ordinary and necessary business errand
7	Office → home, via the supermarket	Split	The office-to-supermarket leg may qualify; supermarket-to-home is personal
8	Home → conference in another city	Yes	Business travel, subject to the usual substantiation rules

Rows 3 and 4 carry the most weight in practice, and both deserve unpacking.

The home office changes the starting point

If your home qualifies as your principal place of business, drives from there to a client, a supplier, or a job site are business mileage from the first mile. The home office is a work location, so leaving it is not commuting.

The qualification is the hard part, not the mileage consequence. The space needs to be used regularly and exclusively for business and to be your principal place of business — which typically means you conduct administrative or management activities there and have no other fixed location where you do so.

Where this trips people up: claiming home-office-based mileage while also maintaining a regular office elsewhere. In that arrangement the drive from home to the regular office remains a commute.

Temporary work locations are not commutes

A work location is temporary when the assignment is realistically expected to last a year or less, and actually does. Driving from home to a temporary site is generally business mileage even when the site looks like an office.

Two failure modes are worth watching:

• Expectation changes. If a nine-month assignment is extended past a year, the treatment changes from the point the expectation changed — not retroactively, and not from the start.
• Indefinite from the outset. An assignment expected to run more than a year is not temporary even if it ends early.

Because the test turns on what was realistically expected and when, the contract or engagement letter is part of the mileage evidence. Keep it with the log.

The errands that quietly fail

Three patterns account for most of the miles that get removed on review.

The chained personal errand. You leave a client, stop at the pharmacy, then drive home. The client-to-pharmacy leg is arguable; pharmacy-to-home is personal. Logging the whole run as one business trip overstates it. Log the legs separately — that is what the leg-level structure of a mileage record is for.

The scenic detour. A route materially longer than the direct one needs a business reason for the extra distance. Traffic and road closures are fine reasons. A stop that had nothing to do with work is not.

The weekend office visit. Going to your regular workplace on a Saturday is still commuting. The day of the week does not change what the location is.

What the record has to show

Four elements per trip, every trip:

• Date — when the drive happened
• Destination — where you went, specifically enough to identify it
• Business purpose — why, in a few words that would still make sense in three years
• Mileage — the business miles for that trip

Plus one annual figure: total miles driven for the year, which is what turns business miles into a business-use percentage.

The purpose field is where reconstructed logs fall apart. “Client visit” is thin. “Site survey — Harper Ltd, Elm Street project” identifies the engagement and would still be verifiable later. The extra six words cost nothing at the time and are the difference between a record that stands and one that invites questions.

Why the classification is worth the effort

At the IRS standard mileage rate of 76 cents per mile — the rate for travel from July 1, 2026, up from 72.5 cents in the first half of the year — the arithmetic is direct:

• 4,000 correctly classified business miles = $3,040 deduction
• The same 4,000 miles logged without a stated purpose = a deduction you may not be able to defend

The rate does not change based on how carefully you logged. What changes is whether the deduction survives scrutiny. Mileage is one of the more frequently examined deductions precisely because it is easy to estimate and hard to reconstruct — which cuts both ways: a specific, contemporaneous log is unusually strong evidence.

Getting the classification right without doing it by hand

The reason mileage logs decay is not that the rules are hard. It is that classification is a small task repeated several hundred times a year, and small repeated tasks lose to everything else on the calendar.

MileTrack detects drives automatically and keeps business, commute, and private as separate types rather than one bucket. Saved places and repeated routes drive the suggestions, so a route you have already classified is proposed correctly the next time — and the purpose field travels with the trip into the export. The business, commute, and private split is shown end to end on the US page.

Exports carry date, origin, destination, distance, purpose, and vehicle context in PDF, CSV, and XLSX, which are the fields this guide has been describing throughout.

Related guides

• Is Commuting Mileage Deductible? IRS Rules + 5 Examples
• Mileage Log Requirements for IRS: What to Record and How to Store It
• Independent Contractor Mileage for Taxes: End-to-End Claim Workflow

Tax note: educational content only, not tax advice. Confirm your own circumstances with a qualified professional before filing.