How to Calculate Car Allowance for Employees: FAVR, Mileage, and Flat

To calculate a car allowance for employees in a way the IRS accepts, pick one of three recognized methods — a cents-per-mile reimbursement tied to the federal standard rate, an actual expense calculation based on documented costs, or a Fixed and Variable Rate (FAVR) plan — and run the payments through an accountable plan. Do that and the reimbursements stay off the employee’s W-2 and off the employer’s payroll tax base. Skip the substantiation piece, and every dollar becomes taxable wages. The IRS standard mileage rate for 2026 is 72.5 cents per mile, and it anchors two of the three approaches.¹

Cents-Per-Mile Reimbursement

The cents-per-mile method ties each payment directly to verified business miles. The employee logs trips, the employer multiplies total business miles by the federal standard mileage rate, and the result is the reimbursement. For 2026, that rate is 72.5 cents per mile, up from 70 cents in 2025.¹ An employee who drives 800 verified business miles in a month receives $580.

When reimbursed at or below the federal rate under an accountable plan, the payment is not reported as income and neither party owes payroll tax on it. If an employer chooses to pay above the federal rate, the excess must be reported as wages in Box 1 of the employee’s W-2, while the portion up to the standard rate goes in Box 12 under Code L as a nontaxable reimbursement.²

This method works well for roles with predictable driving. It falls short for high-mileage employees, because the standard rate may not fully cover ownership costs like insurance and depreciation for someone putting 30,000 business miles a year on a vehicle.

Actual Expense Method

Instead of the standard mileage rate, an employer can reimburse based on documented actual costs. The employee tracks every vehicle expense for the year, then applies the business-use percentage. If someone drives 12,000 total miles and 8,000 are for business, the business-use percentage is 66.7 percent. That percentage is multiplied by total vehicle costs, which include fuel, oil changes, tires, insurance, registration, and depreciation.

Depreciation has a ceiling. For passenger vehicles placed in service in 2026, the IRS caps first-year depreciation at $20,300 if bonus depreciation applies, or $12,300 without it. In subsequent years the limits are $19,800 (second year), $11,900 (third year), and $7,160 for each year after that.³ These caps prevent employers from reimbursing inflated depreciation on luxury vehicles.

The actual expense method is more work than cents-per-mile, but it can produce a fairer result when fuel prices spike or when employees drive vehicles with very different operating costs. An employer cannot switch freely between the two methods mid-year, so the choice is typically locked in at the start of each tax year.

Fixed and Variable Rate (FAVR) Plans

A FAVR plan is the most precise calculation method, splitting the allowance into two components. The fixed portion covers ownership costs like insurance, registration, and depreciation, calculated using a standard vehicle that represents what employees in the plan would reasonably drive. The variable portion reimburses operating costs like fuel and maintenance based on actual miles driven, using a cents-per-mile rate tied to the employee’s work location.

FAVR plans come with strict IRS eligibility rules. At least five employees must be covered by FAVR allowances at all times during the year. Each participating employee must substantiate at least 5,000 business miles annually, or 80 percent of the plan’s assumed annual business mileage, whichever is greater. The employee must own or lease the vehicle, and its original cost when new must be at least 90 percent of the standard vehicle cost used in the plan’s formula.⁴ For 2026, the standard automobile cost in a FAVR plan cannot exceed $61,700.¹

The model year of the vehicle also cannot differ from the current calendar year by more than the retention period built into the plan.⁴ In practice, employees driving older vehicles may not qualify. FAVR is best suited for organizations with a sizable mobile workforce, where the administrative overhead is justified by more accurate, tax-free reimbursements.

What About a Flat Monthly Allowance?

Paying a flat amount each pay period regardless of miles driven is the simplest approach, and it is the one most employers get wrong. A $600 monthly payment with no mileage tracking is a non-accountable arrangement by definition. The employer must add the full amount to the employee’s wages, withhold federal income tax, and pay Social Security, Medicare, and federal unemployment tax on it.⁵ An employee receiving $600 might net closer to $400 after withholding.

Employers who want the predictability of a flat payment need to pair it with mileage substantiation. That effectively converts it into an accountable plan on a fixed payment schedule, with a true-up (or return of excess) when substantiated miles come in below what the flat amount covered.

The Accountable Plan Wrapper

Whichever calculation method you use, the IRS classifies every reimbursement arrangement as either accountable or non-accountable, and that classification decides whether payments are taxable. Under 26 U.S.C. § 62, reimbursed employee expenses qualify as above-the-line deductions only when paid through an arrangement that meets the statute’s substantiation and return-of-excess requirements.⁶ The Treasury regulation sets out three conditions:⁷

Business connection. Every reimbursed expense must relate to services performed as an employee.
Substantiation. The employee must provide adequate documentation of the expenses within a reasonable time.
Return of excess. Any reimbursement that exceeds substantiated expenses must be returned to the employer within a reasonable time.

Meet all three and the reimbursement stays off the employee’s W-2 entirely. Fail any one and the IRS treats every dollar as wages subject to income tax, Social Security, Medicare, and federal unemployment tax.⁷ There is no partial credit.

Which Miles Actually Count

The IRS draws a hard line between business travel and commuting. Driving from home to a regular workplace is commuting, and commuting miles are personal expenses no matter how far the employee lives from the office. Making phone calls or picking up a coworker on the way does not convert a commute into a business trip.²

Business mileage generally starts once the employee leaves their regular workplace, or tax home, and travels to another location for work. The tax home is the entire city or general area where the main place of business is located, not necessarily where the employee lives.⁸ Driving between two work sites during the day, visiting clients, or traveling to a job site outside the metropolitan area all count.

Temporary work locations get special treatment. If an employee has a regular office but is assigned to a temporary work location expected to last one year or less, the daily round-trip from home to that temporary site qualifies as deductible business mileage.² Once the assignment is expected to exceed one year, the temporary location becomes a regular workplace, and the drive becomes a non-reimbursable commute. Build this distinction into the mileage policy, because reimbursing commuting miles under an accountable plan violates the business connection requirement and can reclassify the entire arrangement.

Substantiation Deadlines

The IRS defines “reasonable period of time” using specific safe harbor windows. Stay within these and the timing side of the accountable plan test is automatically satisfied:²

Advances may be issued no more than 30 days before the employee incurs the expense.
Expenses must be substantiated within 60 days after they are paid or incurred.
Excess amounts must be returned within 120 days after the expense is paid or incurred.
If the employer issues quarterly statements asking employees to account for outstanding advances, the employee has 120 days from the statement date to respond.

The mileage log itself has to document the date of each trip, the destination, and the business purpose. A monthly entry that says “various client visits, 200 miles” is not adequate. Each trip needs its own entry. GPS-based mileage apps capture this automatically and produce the kind of contemporaneous records that hold up in an audit. Employers using the actual expense method also need receipts for fuel, maintenance, insurance, and other costs, plus a record of total miles driven so the business-use percentage can be calculated.

What Non-Compliance Costs

When a car allowance plan fails accountable plan standards, the consequences land on the employer. The IRS treats the entire payment as supplemental wages, requiring income tax withholding plus the employer’s share of Social Security (6.2 percent), Medicare (1.45 percent), and federal unemployment tax. Reclassification is not prospective either: on audit, the IRS can assess back taxes on every payment made during the open audit period, and responsible persons can face the trust fund recovery penalty equal to 100 percent of the income tax, Social Security, and Medicare taxes that should have been collected.⁵

Common triggers for reclassification include paying allowances without any mileage documentation, reimbursing commuting miles as business travel, failing to collect excess reimbursements within 120 days, and paying identical amounts to employees whose driving looks nothing alike. An arrangement that pays a salesperson driving 2,000 business miles a month the same as a desk-based manager driving 200 reads as compensation dressed up as reimbursement, and the IRS treats it that way.

Why Employees Cannot Fix a Bad Plan on Their Own Return

Before 2018, an employee who received an inadequate reimbursement, or none at all, could deduct unreimbursed business vehicle expenses as a miscellaneous itemized deduction. The Tax Cuts and Jobs Act suspended that deduction starting in 2018, and later legislation has made the elimination permanent. Unreimbursed employee business expenses are no longer deductible for any employee other than certain educators.

That changes the stakes for employers. If the plan is non-accountable and the after-tax payment does not cover actual vehicle costs, the employee has no way to recover the difference at tax time. A few states, including California, Illinois, and Massachusetts, impose their own reimbursement obligations that can add liability when a plan falls short. For employers everywhere, though, the practical effect is the same: a well-structured accountable plan, built on one of the three calculation methods above, is the only way to make employees whole for business driving without anyone overpaying in tax.

1
IRS.gov. Notice 2026-10 – 2026 Standard Mileage Rates
2
Internal Revenue Service. Publication 463 (2025), Travel, Gift, and Car Expenses
3
Internal Revenue Service. Rev. Proc. 2026-15
4
Internal Revenue Service. Rev. Proc. 2001-54
5
Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
6
Office of the Law Revision Counsel. 26 U.S. Code 62 – Adjusted Gross Income Defined
7
eCFR. 26 CFR 1.62-2 – Reimbursements and Other Expense Allowance Arrangements
8
Internal Revenue Service. Topic No. 511, Business Travel Expenses