Ten mileage cases compared, from the long commute to the app export

What to take away

Ten mileage cases compared

Each case below names the rule and the document behind it, and each carries example arithmetic at published rates.

1. The long commute

An hour each way to one client site for eight months looks like business travel. It is tiring, and it is for work. Revenue Ruling 99-7 supplies the test: an assignment expected to last a year or less is temporary, so the drives are deductible.

Past a year, the site becomes a regular place of work and the same miles are commuting. A 45-mile round trip, five days a week, runs about 11,700 miles a year. At 70 cents a mile, that is roughly $8,190 if the site stays temporary, and nothing if it does not.

What it turns on: whether the site is a regular place of work. Distance is not part of the definition, and how unpleasant the drive is carries no weight.

2. The supply stop on the way in

The same driver stops at a supplier on the morning run and treats the whole journey as business. The stop is a business errand, so the miles from the supplier to the site can qualify. The miles from home to the supplier usually do not.

Employees cannot deduct unreimbursed mileage at all. The Tax Cuts and Jobs Act suspended Form 2106 and the other miscellaneous itemized deductions for 2018 through 2025, though a few states still allow the expense. A self-employed driver reports the same errand on Schedule C.

What it turns on: whether the stop converts a commute or merely interrupts it. Log what happened and let the preparer apply the rule rather than deciding it yourself in the parking lot.

3. The spare-room office

A consultant works mostly from a room at home and drives from there to clients, treating every trip as business mileage.

What it turns on: whether the home qualifies as the principal place of business under Publication 587. That is a specific test, not a description of where the laptop lives.

The simplified home office method pays $5 a square foot up to 300 square feet, a maximum of $1,500 a year. The regular method uses actual costs and requires a space used only for work.

A home office claim also changes which business deductions apply to the same room.

4. The client visit that became lunch

A trip out to a customer ends with a personal errand nearby. Split the day: the miles to the customer and back are business, and the detour miles are not. Business meals are 50% deductible, and lunch with no business purpose is not deductible at all.

What it turns on: whether the record shows both purposes and enough detail to separate them. The order of events does not make the whole day business.

5. The app left on default

A driver installs a tracking app in January, never reviews its classifications, and exports the year in April.

MileIQ, Everlance, Driversnote, TripLog and Stride all sort drives into categories automatically. Paid tiers typically run $5 to $10 a month, or $60 to $110 a year, and free tiers cap automatic tracking: MileIQ's free plan records 40 drives a month.

What it turns on: whether those classifications reflect what actually happened. A 20-mile round trip filed under the wrong label is $14 at 70 cents a mile, and two a week for a year is about $1,450. An unreviewed export is an assumption with a timestamp.

6. The missing odometer

Every trip is logged, but nobody wrote down the reading at the start or the end of the year.

Business use share is business miles divided by total miles, and the denominator comes from those two readings. Publication 463 asks for total miles for the year as well as business miles. At 12,000 total miles and 6,000 business miles, the share is 50%.

Under the actual expense method that share applies to every cost: gas, insurance, repairs, tires and depreciation. If the costs run $9,000, the deduction is $4,500.

What it turns on: the business-use share, which needs a denominator. Under the actual expense method this is not a detail; it is the calculation.

7. The bookkeeper who categorized fuel

The business claims the standard per-mile amount of 70 cents for 2025, and the bookkeeper also posts fuel and repairs to an expense account out of habit.

The rate already bundles fuel, repairs, insurance, registration and depreciation. Claiming the bundle and its contents is claiming one cost twice. Parking fees and tolls are the exception, and those stay deductible on top of the rate.

What it turns on: what the per-mile figure is designed to cover. The 2024 rate was 67 cents and the 2023 rate 65.5 cents, and each covered the same list.

8. The vehicle that changed method

A car was claimed at the standard rate in its first business year. Three years later the actual expense method looks better on paper.

The first year decides. Publication 463 lets a vehicle that starts on the standard rate move to actual expenses later. A vehicle that starts on actual expenses cannot move back to the standard rate, because depreciation has been claimed.

Bonus depreciation is 40% for 2025, after 60% in 2024, and both it and Section 179 come through Form 4562 on the actual expense method.

What it turns on: whether a switch is allowed for that vehicle at all, given how it is owned and what depreciation has been claimed. The prior returns hold the answer, and the arithmetic does not.

9. The company car driven home

An entity owns the vehicle, and an owner uses it at weekends.

Personal use of a business vehicle is taxable wages. The IRS commuting valuation rule values a one-way commute at about $1.50 for 2025, and only under a written policy that bans other personal use. Weekend miles are valued in full through the lease value rule in Publication 15-B and reported on Form W-2.

This is its own subject with its own consequences, and it is a common blind spot in single-owner companies. Where the entity sits for tax purposes is the starting point, which is why entity tax treatment comes before this question.

What it turns on: how personal use of a business vehicle is reported.

10. The reimbursement that became pay

A business pays a flat monthly amount to an owner for driving, with no log behind it.

An accountable plan keeps that money out of wages. Treas. Reg. 1.62-2 asks for three things: a business connection, substantiation within 60 days, and return of any excess over the actual expense within 120 days. A flat $500 a month with no log meets none of them.

What it turns on: whether the arrangement meets the conditions for a reimbursement. Where it does not, the payments can end up treated as compensation, and the payroll tax overview explains why that changes both sides of the transaction.

The ten cases at a glance

What all ten turn on

Five questions, and only one of them is arithmetic. That ratio is the honest summary of this whole subject.

Turning your own driving into a case

Take one week of driving and write each trip as a case: what happened, what the record shows, and what a preparer would ask about it. Where you cannot answer the third part from a document, you have found the record to start making.

The record requirements for vehicle claims are set out in Publication 463 for the year it covers, and the mileage rates overview explains how 70 cents for 2025 and 67 cents for 2024 fit the two methods. How long any of it has to survive is in tax records and audits.

Common questions