If employees drive personal vehicles for your business, you need a written mileage reimbursement policy. Without one, you risk overpaying, under-reimbursing, exposing employees to unexpected tax bills, or triggering payroll tax obligations you didn’t expect. According to data from Motus, roughly 62% of small businesses operate without a written mileage policy — and many of them are paying a hidden cost as a result.
This guide walks through the IRS accountable plan rules, what every mileage reimbursement policy must include, how to set the right rate, and how to enforce the policy consistently.
Why Every Business Needs a Mileage Reimbursement Policy
When an employee drives their personal car on company business, they incur a real cost. If you don’t reimburse them, you may be violating state law — California, Illinois, and Massachusetts all have statutes requiring employers to reimburse employees for necessary business expenses, including mileage.
But there’s also a tax dimension. Reimbursements are only tax-free to employees when they’re made under an IRS accountable plan. Without an accountable plan, every dollar you pay for mileage becomes taxable wages. That means the employee owes income tax on it, you owe employer FICA on it, and you have to run it through payroll. A simple policy document prevents all of that.
The IRS Accountable Plan Requirement
The accountable plan rules are the foundation of any mileage reimbursement policy. To qualify as an accountable plan, your reimbursement arrangement must meet three conditions:
Business connection: The expense must be an ordinary and necessary business expense — driving to client meetings, job sites, offsite work locations, or required business errands. Normal commuting from home to the regular office does not qualify.
Adequate accounting: Employees must substantiate each reimbursement claim with a mileage log that includes the date, origin, destination, business purpose, and miles driven. They must submit this documentation within a reasonable period — the IRS considers 60 days to be reasonable.
Return of excess: If you advance or reimburse more than the actual expense, the excess must be returned within a reasonable time (120 days is the IRS benchmark).
For more detail on how accountable plans work, see our guide to accountable plan mileage reimbursement.
Setting the Reimbursement Rate
The rate you pay per mile has significant tax and legal implications. The IRS standard mileage rate for 2026 is 72.5 cents per mile, and it serves as the benchmark for most employer policies.
At the IRS rate (72.5¢/mile): This is the most common choice. Reimbursements at or below the IRS rate are tax-free to employees and fully deductible for the employer. No payroll processing required on the reimbursed amounts.
Below the IRS rate: Employees can technically deduct the unreimbursed difference — but only on Schedule A as a miscellaneous deduction, which requires itemizing and is subject to the 2% AGI floor. In practice, most employees can’t benefit from this. Paying below the IRS rate risks losing good employees and potential state law violations.
Above the IRS rate: Any amount you pay above the IRS standard rate is considered excess. That excess is taxable wages to the employee, subject to withholding and employer FICA. The IRS rate portion remains tax-free; only the overage is taxable.
For most businesses, reimbursing at exactly the IRS rate is the cleanest choice: tax-free, fully deductible, no complex payroll calculations, and legally defensible. For employees who drive significantly, consider whether a car allowance or company car arrangement might be more cost-effective.
Template: Key Sections of an Effective Policy
A mileage reimbursement policy doesn’t need to be long, but it needs to cover every element the IRS and your employees expect. Here is the structure:
Section 1 — Purpose State clearly that the policy establishes the process for reimbursing employees who use personal vehicles for approved business travel.
Section 2 — Eligibility Identify which employees and which roles qualify. Not every employee automatically qualifies — define it explicitly (e.g., “all full-time employees in field sales and service roles”).
Section 3 — Qualifying Trips Specify which trips are reimbursable. Include: travel between company locations, travel to client or customer sites, travel to offsite meetings or training, and any other approved business travel. Explicitly exclude: commuting between home and the regular office, personal errands, and non-approved travel.
Section 4 — Reimbursement Rate State the per-mile rate. Example: “The company reimburses at the IRS standard mileage rate, currently 72.5 cents per mile for 2026. This rate is reviewed annually.” Including an annual review clause avoids having to reissue the policy every January.
Section 5 — Documentation Requirements Define exactly what employees must submit with each claim. At minimum: date, starting point, destination, business purpose, and total miles. Specify that mileage tracking apps are acceptable (and preferred) documentation tools.
Section 6 — Submission Process and Deadlines State how employees submit claims (expense report, app submission, email) and by when. The IRS considers 60 days from the trip date to be a “reasonable” submission window. State your deadline clearly — many companies use monthly or bi-weekly submission cycles.
Section 7 — Approval Process Name the approving authority (direct manager, finance department) and the turnaround time for approval and payment.
Section 8 — Dispute Resolution Provide a clear process for employees to dispute denied claims or raise questions about the policy.
How to Enforce the Policy and Track Compliance
The weakest point in most mileage reimbursement programs is enforcement. Employees submit estimates, forget to log trips, or submit paper reports weeks late. Managers approve without checking. Year-end audits find inconsistencies.
The most effective solution is to require employees to use a mileage tracking app that generates IRS-compliant reports automatically. When an employee uses Tripbook, every trip is logged with date, GPS-verified distance, start and end location, and business purpose. The app generates a clean report the employee submits directly to the approver.
This solves three problems at once: it ensures the documentation meets IRS accountable plan requirements, it eliminates estimated or inflated mileage, and it makes the submission process fast enough that employees actually comply with deadlines.
For employees, this matters too. A complete mileage log protects them if the IRS ever asks questions. For an overview of what the IRS requires in a mileage log, see our IRS mileage log requirements guide.
A Policy That Protects Everyone
A written mileage reimbursement policy isn’t just paperwork — it’s the legal mechanism that makes reimbursements tax-free, keeps your business in compliance with IRS rules and state labor laws, and sets clear expectations for employees. The cost of not having one shows up in payroll tax bills, employee disputes, and audit exposure.
Use the sections above to build your policy, pair it with a mileage tracking requirement, and review the rate each January when the IRS publishes the new standard rate. The whole setup takes an afternoon and saves headaches for years.
Download Tripbook and give your employees the IRS-compliant mileage reports your accountable plan requires.
