Which trips count as reimbursable business mileage for commuting and home-based workers, and how are those miles documented?

What rule separates a commute from business travel?

IRS Revenue Ruling 99-7 sets the test: daily transportation between a taxpayer's residence and a work location is a nondeductible commuting expense unless one of three exceptions applies. A trip is judged by where it starts and the status of both ends, never by the destination alone.

Under Publication 463, a commute stays personal no matter how far the home is from the regular place of work, and even if the worker works during the trip; business calls or a business discussion in the car do not change the trip from personal to business. Travel between work locations sits on the other side of the line: Publication 463 says someone who works at two places in one day, whether or not for the same employer, can deduct the cost of getting from one workplace to the other.

Why must a trip be classified before it is reimbursed?

Publication 463's first rule for an accountable plan is a business connection: the employee must have paid or incurred deductible expenses while performing services as an employee.

A commute cannot meet the first rule however carefully it is logged: Publication 463 says reimbursements for nondeductible expenses do not meet it and are treated as paid under a nonaccountable plan. Paying for a trip, or asking the worker to make it, does not turn it into business mileage; the classification does. Per-mile rates, allowances, plan paperwork and payroll treatment are separate questions.

Which home-to-work trips are business travel?

Revenue Ruling 99-7 treats daily trips between home and a work location as follows:

Publication 463 says a metropolitan area generally includes the area within the city limits and the suburbs that are considered part of that metropolitan area.

When is a work location temporary rather than regular?

Publication 463 decides it by the realistic expectation of how long work at the location will last:

The same drive can change category with nothing different on the road. A technician who reports to the employer's shop, and whose home is not a principal place of business, is sent to a customer's plant for an installation expected to take five months. Under the second exception, home-to-plant trips are business travel. In month four the customer extends the work, which is now realistically expected to run 16 months in total. From the date of that change the plant is not temporary, no exception applies, and the same trips are commuting.

Nothing in the routine flags that change, so record each site's expected end date when it is first classified, re-check it at every extension, renewal or change order, and note the date the expectation passed one year.

Neither Revenue Ruling 99-7 nor Publication 463 says how often a worker must attend a location for it to be a regular work location. Treat a site visited now and then over more than a year as a case to confirm before relying on either answer.

When is the home the principal place of business?

Publication 463 refers readers to Publication 587, Business Use of Your Home, to decide whether a home office qualifies. Publication 587 requires exclusive use, meaning a specific area of the home used only for the trade or business, and regular use, meaning that area is used for business on a regular basis. To decide whether the home is the principal place of business, Publication 587 weighs the relative importance of the activities performed at each place of business and the amount of time spent at each. Under Publication 587, a home office also qualifies if both of these are true:

• It is used exclusively and regularly for administrative or management activities of the trade or business.
• The worker has no other fixed location where they conduct substantial administrative or management activities of the trade or business.

Publication 587's examples of such activities include billing customers, keeping books and records, ordering supplies and setting up appointments. Publication 587 says the home office is not disqualified when others do the administrative work elsewhere (for example, another company does the billing from its own place of business), when that work is done in places that are not fixed locations, such as a car or hotel room, or when minimal administrative work is occasionally done at a fixed location outside the home.

Doing some work at home before leaving does not settle it. Revenue Ruling 99-7 says that when a home office does not meet the principal place of business requirements, the business activity there is not enough to overcome the inherently personal nature of the residence, and trips between the residence and regular work locations are personal. Before treating home as the start of business trips, keep a dated note of the space, the business work done there and how often, and whether the worker does substantial administrative or management work at another fixed location.

For employees the position is less settled. Revenue Ruling 99-7 notes that section 280A limits an employee's home-office expenses to cases where the exclusive and regular use is for the convenience of the employer. The ruling does not say whether that condition also governs when an employee's home counts as the principal place of business for classifying trips, so confirm it with a tax adviser before reimbursing an employee's trips from home on that basis.

How do the trips work out for each kind of worker?

What if the worker reports to an employer location?

Unless the home is the principal place of business, home to the office is commuting, and so is home to any site that is not temporary. The rest of this worker's work driving, office to customer, customer to customer, or home to a temporary site in the same trade or business, is business travel.

What if the worker is fully remote?

With no employer location to attend, the home decides almost everything. If it is the principal place of business, every trip from home to another work location in the same trade or business is business travel. If it is not, and the worker has no regular workplace away from home, only the first exception remains: trips to temporary sites outside the metropolitan area are business travel, and other home-to-site trips are commuting. Under Revenue Ruling 99-7, a trip to an employer office inside the metropolitan area is commuting whether that office is regular or temporary. The office's status matters in two places: a trip to an office outside the metropolitan area is business travel only if the office is a temporary work location, and an office that is a regular work location away from home would bring the second exception into play for the worker's trips to temporary sites. Flag those two kinds of trip for confirmation.

What if the worker visits several sites a day with no fixed workplace?

Publication 463's example covers a worker with no regular office and no home office: the first business contact inside the metropolitan area is considered the office, so the drive from home to that contact and the drive home from the last contact are commuting, while driving from one client or customer to another is deductible. The first and last legs become business travel only if the site is a temporary work location outside the metropolitan area or the home is the principal place of business.

How is a day that mixes business and personal driving split?

Publication 463 gives two rules. When a worker detours for a personal reason between two work locations, no more than the cost of going directly from the first location to the second counts. Publication 463 also says minimal personal use, such as a stop for lunch on the way between two business stops, does not interrupt business use, and a round trip or uninterrupted business use can be recorded as a single use.

So a lunch stop leaves a business leg intact, but a detour that adds miles does not. A worker who drives from one customer to the next by way of a school pickup, 17 miles instead of the direct 11, has 11 business miles. Record both figures and the reason; the other 6 are personal.

How are one home-based worker's trips classified?

Riley works fully remotely, has no employer location to attend, and drives a personal car. Clients A and B are inside Riley's metropolitan area and the supplier plant is outside it. The middle columns show each outcome if Riley's home office qualifies as the principal place of business and if it does not.

On the day of trips 1 to 3 Riley drives 28 miles: 25 are business miles if the home office qualifies and 6 if it does not. If Riley is an employee, the "home qualifies" column also depends on the convenience-of-employer question above.

What must each trip record show?

For mileage, Publication 463's Table 5-1 requires records of the mileage for each business use and the total miles for the year, the date of the use of the car, the business destination, and the business purpose. Publication 463 also says to record these at or near the time of the use and to support them with sufficient documentary evidence; a log kept on a weekly basis that accounts for use during the week counts as a timely kept record. Publication 463 generally requires a written statement of business purpose, but not where the purpose is clear from the surrounding circumstances. Under Publication 463's accountable-plan rules, the employee must give the employer the same type of records and supporting information the employee would have to give the IRS if it questioned a deduction.

Those elements prove the miles. To make the classification supportable too, add these fields to each line:

• Start and end points. Name each end as home, the regular workplace or a specific site, because the starting point decides most trips.
• Status of each end. Mark it regular, temporary with its expected end date, or home as the principal place of business with the date that was confirmed.
• Rule applied. State whether the trip ran between work locations, fell under one of the three exceptions, or was commuting.
• Detours. Show the actual miles, the direct-route miles and the business miles claimed.
• Decision. Record who classified the trip, when, and whether it is flagged.

To test an existing log, pick any line and ask whether it shows where the trip began and why the destination qualified. A log of dates and distances substantiates miles, not the decision. Records for employees who drive company-owned vehicles are a separate question.

Who records the classification, and how is a doubtful trip handled?

Publication 463 says an employer should tell employees what method of reimbursement is used and what records they must provide. That guidance does not say who classifies each trip; the steps below are a control the reimbursing business sets for itself. Run the decision in this order:

1. Write the classification rule once, from the exceptions and worker patterns above, and apply it by arrangement rather than by person, so two workers who drive the same pattern get the same answer.
2. Record each worker's arrangement and its effective date: which location is regular, whether the home has been confirmed as the principal place of business, and each temporary site's expected end date.
3. Have the worker propose a classification for each trip, and have a named reviewer approve it on the log or expense report, with the date.
4. Flag rather than guess when a site's expected duration is extended or its work is nearing a year, a site has been visited now and then for more than a year, a fully remote worker's trip turns on whether an employer office is regular or temporary, a home office is unconfirmed, an employee's trips start from a home office, or the starting point is unclear. Keep a flagged trip out of the business-mileage total until it is resolved, then record the answer and who gave it.
5. When an arrangement changes, record the effective date. Trips before it keep their classification and trips after it follow the new facts, as the one-year rule does for a site whose expected duration changes.

What changes when the driver is self-employed?

The trip rules do not: Publication 463 says most employees and self-employed persons can use its chart of when transportation expenses are deductible, though it says not to use the chart when the home is the principal place of business, and a self-employed worker's home office is tested under Publication 587 without the employee convenience question. Who holds the record does change. Publication 463's section for independent contractors says a contractor reimbursed for travel expenses incurred on behalf of a client should give the client an adequate accounting, must otherwise include the reimbursements in income, and must keep adequate records either way. That wording covers travel and gift expenses and does not mention local transportation, and how a business pays and reports a contractor's mileage is a separate question.

How long must the records and the classification basis be kept?

Publication 15 (2026) tells employers to keep all records of employment taxes for at least 4 years, and its list of those records includes records of fringe benefits and expense reimbursements provided to employees, including substantiation. Keep the classification basis with the log for the same period, because the arrangement records, expected end dates, home-office notes and reviewer decisions are what show why each trip was paid.

Do not count on the worker's copy. Publication 463 says employees who give their records and documentation to their employers and are reimbursed generally do not have to keep copies. File each worker's logs and classification basis by period, so any payment can be traced back to the trip and the decision behind it.

How long a self-employed worker keeps records for their own deduction, and how long a business keeps records of a contractor's mileage reimbursement, are separate questions.