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How the Standard Mileage Rate, accountable plans, Publication 463, and the comparison with international rates work — in one pillar guide.
The Internal Revenue Service (IRS) publishes an annual Standard Mileage Rate that has become the most widely used reference in the world, even outside the United States. For 2025, the rate is US$0.70 per mile for business use, US$0.21 per mile for medical or armed-forces moving, and US$0.14 per mile for charity. That rate is not arbitrary — the IRS commissions an annual independent study by Runzheimer (now Motus) that measures the real cost of operating an average vehicle in the US, including fuel, maintenance, depreciation, insurance, registration, and taxes.
The international relevance of that rate is threefold. First, multinationals with offices in several countries use the IRS rate as a natural ceiling when defining global policies — paying above without local justification looks like disguised wages. Second, Brazilian and Mexican companies with American parents inherit the "accountable plan" framework as the foundation for designing their local policies. Third, any honest international comparison must start with the American number. The article IRS Standard Mileage Rate 2025: international comparison details how Brazil, Mexico, and Europe position themselves relative to the US benchmark.
The American taxpayer (individual or business) can choose between two methods to deduct mixed-use vehicle expenses: the Standard Mileage Rate or the Actual Expense Method. The choice has long-term consequences. If you choose the Actual Expense Method in the first year the vehicle is placed in service, you are locked into that method for as long as the vehicle is in business use. If you choose the Standard Rate in the first year, you can switch between the two in subsequent years. This asymmetric symmetry is one of the most common sources of error in personal returns of people who drive Uber, Lyft, DoorDash, or do freelance consulting.
The Standard Rate is operationally simpler: multiply documented business miles by the annual rate and you are done. Actual Expense requires detailed tracking of fuel, maintenance, insurance, depreciation (or the Section 179 deduction), registration, and financing interest, with proportional business-use calculation. For most drivers with mid-class vehicles and business mileage between 8,000 and 25,000 miles/year, the Standard Rate produces a larger deduction. For large SUVs, heavy pickups, and luxury vehicles with accelerated depreciation, Actual Expense tends to be more advantageous.
The most important concept for American companies is the accountable plan. Under Reg. 1.62-2(c)(1), an expense reimbursement paid to an employee is non-taxable (does not enter the W-2, no FICA withholding) when it meets three requirements: (1) business connection, (2) substantiation within a reasonable period, (3) returning amounts in excess within a reasonable period. Failing any one of the three transforms the accountable plan into a non-accountable plan, and the entire reimbursement is then treated as taxable wages.
For mileage reimbursement, this means that every trip must be tied to a specific business activity, recorded with date, miles, origin, destination, and purpose, submitted within a reasonable period (typically 60 days), and any overpayment must be returned within a reasonable period (typically 120 days). IRS Publication 463 (Travel, Gift, and Car Expenses) details the framework with numerical examples. The practical difference between the two plans is huge: under an accountable plan, US$5,000 of annual reimbursement is paid in full to the employee; under a non-accountable plan, US$5,000 minus FICA (7.65%), minus federal withholding (12% to 24%), nets between US$3,180 and US$3,730. Companies that pay mileage reimbursement without an accountable plan lose money and expose the employee to double taxation.
Publication 463 is the most-read document in the US when the topic is deduction of travel and vehicle expenses. It covers three blocks: business travel away from home, gift expenses, and car expenses. The car block details what counts as a principal place of business, what counts as commuting (not deductible), what counts as business mileage, and how to handle cars partially used for personal purposes. The most underused concept is "tax home" — the geographic location considered the taxpayer's base of operations. Trips within the tax home are commuting; trips outside the tax home can be deductible. The article US IRS Standard Mileage Rate 2025 brings numerical examples of how to apply this concept.
For self-employed (Schedule C), the mileage deduction enters on line 9 (Car and truck expenses) with detail on Part IV. For employees (W-2), the deduction of unreimbursed employee expenses was suspended through 2025 by the TCJA (Tax Cuts and Jobs Act), except for certain categories (armed forces, qualified police officers, certain teachers). This means, in practice, American employees depend entirely on company reimbursement via accountable plan — there is no longer a meaningful individual mechanism. For corporations (Form 1120, 1120-S, 1065), reimbursement paid appears on the salaries-and-wages line when via non-accountable plan, or on the other-deductions line when via accountable plan.
In an audit, the IRS asks for the mileage log. There is no mandatory official format, but the minimum content is set by Treasury Reg. 1.274-5T(c)(2): date, miles, destination, business purpose. Logs created contemporaneously (on or near the day of the trip) carry far more weight than logs reconstructed afterward. Tax Court case law is clear: logs reconstructed from memory or calendar can be accepted, but with a heavy evidentiary burden on the taxpayer. The good practice is to use an app that records GPS at the moment of the trip and generates the log automatically.
The "estimated annual mileage" rule — common in informal Brazilian practice — is explicitly rejected by the IRS. Estimating 15,000 business miles without a detailed log leads to total loss of the deduction in audit, even if the estimate is realistic. The classic case is Cohan v. Commissioner, but later case law has severely limited the application of the Cohan rule to vehicle expenses via Section 274(d), which requires written substantiation.
The FTR (Federal Travel Regulation), administered by the GSA, sets the rate the federal government pays its employees when they drive in service. That rate follows the IRS Standard Mileage Rate (US$0.70/mile in 2025) and serves as a reference for many federal and state contracts that tie reimbursement to that standard. Companies that provide services to the government, receive federal grants, or administer publicly funded programs typically inherit the GSA rate as a natural cap. The international comparison article (IRS rate 2025 comparative) details how OECD countries position themselves relative to that rate.
Most American states levy state income tax and follow, with small variations, the federal treatment of mileage reimbursement. States with no income tax (Texas, Florida, Tennessee, Washington, Wyoming, Nevada, Alaska, South Dakota, New Hampshire) eliminate that layer. States with divergent treatment — California is the most notable — require the company to reimburse "all necessary expenditures or losses incurred by the employee in direct consequence of the discharge of his or her duties" (Labor Code §2802), making reimbursement mandatory by state law when vehicle use is part of the job. Companies with sales force in California must reimburse even if no federal policy requires it.
Global companies with US, Brazilian, and Mexican operations face the challenge of harmonizing policies. The most defensible practice is to maintain the IRS Standard Mileage Rate as a conceptual reference and adjust the absolute number per country based on a local cost study. For Brazil, that means paying close to the R$0.90 to R$1.40/km range. For Mexico, MX$7.50 to MX$11/km. Documenting the derivation methodology (a Runzheimer-equivalent local study) shields against reclassification both by the IRS in transfer pricing and by local authorities. The article multi-country teams managing mileage details the global governance playbook.
Different sectors have radically different mileage patterns in the US. Outside sales averages 12,000 to 25,000 miles/year per employee. Construction and field service, with frequent visits to many sites, can reach 35,000 miles/year. Each sector has specific traps: remote sales has higher risk of mixing commuting with business; construction has higher incidence of commercial pickup vs. personal vehicle; field service has greater need for granular per-job logging. The articles remote sales teams and construction and field service detail best practices by sector, and the article reimbursement vs. company car compares the two models with break-even calculations.
The IRS has a general statute of limitations of three years from the date of filing for normal audits, six years when there is substantial understatement (>25% of gross income), and indefinite when there is fraud or non-filing. Good practice for mileage reimbursement is to retain logs and reports for seven years, comfortably covering the six-year window. Companies with continuous Big Four audit or SOX requirements should retain for ten years.
The Quilometragem platform generates reports compatible with Publication 463 requirements: every trip includes date, miles (with the Standard Rate applied), origin, destination, purpose, and vehicle. CSV export feeds directly into the main American systems (QuickBooks, Xero, NetSuite, Concur). Monthly reports come pre-formatted as accountable plan attachments, with the complete substantiation that secures non-taxable treatment.
American companies that still pay reimbursement without a formal accountable plan should adopt three measures within 60 days: (1) write and adopt an accountable plan via corporate document, (2) implement automatic mileage logging via app/GPS for the top 10 reimbursers, (3) adjust payroll to zero out tax on the reimbursement. The ROI is direct — between US$1,500 and US$3,000 per employee per year in FICA savings + avoided withholding.
Continue with the cluster: US IRS Standard Rate 2025, international comparison 2025, remote sales teams, construction and field service, reimbursement vs. company car, and multi-country teams. Each one covers a specific angle of US mileage practice.
The IRS published on 17 December 2025 (Notice 2026-03) the Standard Mileage Rate for 2026: **US$0.72 per mile** for business use (a 2-cent increase over 2025), US$0.22/mile for medical or military moving, and US$0.14/mile for charity (fixed by statute since 1998). The 2026 rate reflects the October 2025 Motus study, which measured maintenance and insurance increases that outpaced the fuel-price decline. The accountable plan remains the core framework, and the [IRS Publication 463 (rev. Dec 2025)](https://www.irs.gov/forms-pubs/about-publication-463) consolidated electric-vehicle treatment into a single chapter, removing 2024's ambiguity.
At the state level, California remains the most litigated jurisdiction. *Cassens v. Equifax* (2025, Cal. App.) extended the Labor Code §2802 reading to reimbursements paid below the IRS rate when the employer cannot prove they cover the actual cost. Details and SME implications in Mileage reimbursement in California 2026 (Labor Code 2802).
For companies operating in Canada, the equivalent of the US accountable plan is the **Form T2200 (Declaration of Conditions of Employment)**, which the employer must issue so the employee can deduct employment expenses. The most common practical question — an employee hired in January with the form only signed in March — is covered in T2200 for January-hire employees in Canada, with the procedure accepted by the CRA (Canada Revenue Agency).