Commuting and temporary-site transportation follow different rules
Ordinary commuting between home and a regular workplace is personal transportation. Travel to a temporary work location can be deductible under specific circumstances, including where the taxpayer has one or more regular work locations away from home in the same trade or business. A person with no regular work location can face different rules for temporary sites within the metropolitan area where the person lives and normally works. An owner should therefore not reimburse every client-site mile simply because an engagement is temporary. A qualifying principal-place-of-business home office can also affect travel between home and another work location, but merely answering emails at home does not establish that status. The decision is to classify the actual starting point, regular locations, temporary site, and expected duration before applying a mileage rate.
Separate the regular office trip from client travel
Assume an owner has a regular company office 12 miles from home and a genuinely temporary client site 30 miles from home in the same trade or business. The daily home-to-regular-office commute generally is personal. Depending on the applicable temporary-location rules, direct travel from home to the temporary client site can receive different treatment. If the owner first visits the regular office and then drives 20 miles to the client, the office-to-client business segment is separately identifiable. For ten qualifying round trips totaling 600 business miles, an assumed reimbursement rate of $0.70 would produce $420. The rate is hypothetical, not the current federal rate. The example does not establish that all 600 miles qualify; worksite status must be resolved first. Multiplying personal commuting miles by an authorized mileage rate does not convert them into business transportation.
Document regular locations and expected duration
Create a work-location register showing the company office, recurring client sites, home office if claimed, and temporary engagements. Retain contracts, expected end dates, extensions, actual attendance, and project changes. A work location generally expected to last more than a year can be indefinite rather than temporary under the applicable rules, and a revised expectation can change treatment prospectively. Do not continue the original temporary label after the client expands a three-month engagement into a multiyear assignment. Record the relevant metropolitan area facts if the owner has no regular workplace away from home. Distinguish local transportation from overnight away-from-home travel and tax-home analysis; the rules overlap but answer different questions. A diary entry stating client meeting is useful, but it cannot establish temporary status without the broader work pattern.
Apply accountable reimbursement to the eligible miles
Maintain contemporaneous dates, destinations, mileage, and business purposes and segregate commuting, personal errands, and qualifying business segments. The company should use a consistent approved mileage method and avoid reimbursing the same vehicle costs twice. Parking and tolls need their own classification because a fee incurred during commuting can remain personal even when separately paid. If the owner combines a personal stop with a client visit, document the direct business route and incremental personal miles. Review reimbursements when the worksite's expected duration changes. Do not disguise commuting through a flat monthly car allowance or a reimbursement report that lists the company office as a client. Owner control over the company does not remove substantiation duties. Retain the work-location analysis with the mileage log so a future reviewer can understand why particular home-origin trips were included.
Update the policy as the owner’s work changes
A founder who stops using the company office, begins working mainly at home, or takes a long-term client assignment may need a new transportation analysis. Do not assume last year's reimbursement policy still fits. Confirm any home-office qualification separately and identify when facts changed. Compare the company's reimbursement expense, the owner's personal commuting cost, and any taxable allowance alternative using the actual work pattern. The useful result is a defensible eligible-mile total supported by location and duration records. It is not a generic promise that temporary work permits deducting every journey from home. Resolving that classification before applying the rate lets payroll and bookkeeping process reimbursements accurately and helps the owner budget personal travel costs without expecting the business to fund them tax free.
Sources & further reading
Consult the original guidance and its effective dates. These references support the educational discussion; their application depends on the specific facts.