Idaho Mileage Reimbursement 2026: Laws, IRS Rate & Employer Rules

If employees use their personal vehicles for work in Idaho, there is no single mileage reimbursement rate that every private employer is required to pay.

Many employers use the IRS standard mileage rate as a benchmark. 

In 2026, that rate changed mid-year. The optional business mileage rate is 72.5 cents per mile from January 1 through June 30, 2026, and 76 cents per mile beginning July 1, 2026.

Idaho also has separate rules for official state travel and workers’ compensation medical travel. Those rules can use a different rate from the IRS business mileage rate.

Here is what Idaho employers and employees should know about mileage reimbursement in 2026.

What Is the Idaho Mileage Reimbursement Rate for 2026?

Idaho does not have a mandatory mileage reimbursement rate that applies to ordinary business driving by all private-sector employees. 

Employers that reimburse business mileage often use the optional IRS standard mileage rate as a benchmark.

The IRS business mileage rates for 2026 are:

• January 1 through June 30, 2026: 72.5 cents per business mile
• July 1 through December 31, 2026: 76 cents per business mile

The IRS increased the rate mid-year following recent increases in fuel prices. 

The revised 76-cent rate applies to qualifying business transportation expenses paid or incurred on or after July 1, 2026.

The IRS standard mileage rate is optional. 

Private employers can use it for a Cents-Per-Mile reimbursement program or choose another reimbursement structure that better reflects their employees’ driving patterns and costs.

Do Private Employers Have to Reimburse Mileage in Idaho?

Idaho does not establish a general per-mile reimbursement requirement for ordinary private-sector business driving.

That gives employers flexibility in how they reimburse employees who use personal vehicles for work. 

An employer might use the IRS mileage rate, establish another CPM rate, or use a mileage reimbursement program designed around employees’ real, business-required vehicle costs.

Employers should also consider employment agreements, collective bargaining agreements, written company policies, and other requirements that apply to a specific workforce.

Workers’ compensation travel is a separate situation under Idaho law and has its own reimbursement requirements.

When Can Mileage Reimbursement Be Tax-Free in Idaho?

The tax treatment of mileage reimbursement depends on how the reimbursement program is structured and documented.

The Idaho State Tax Commission says employers do not have to withhold Idaho income tax on employee business-expense reimbursements made under an accountable plan. 

Reimbursements made under a nonaccountable plan are subject to Idaho income tax withholding.

Under IRS Publication 463, an accountable plan generally requires three things:

1. The expense must have a business connection.
2. The employee must adequately account for the expense within a reasonable period.
3. The employee must return any excess reimbursement within a reasonable period.

For mileage, employees should maintain adequate records showing details such as the mileage driven, date, destination, and business purpose of the trip.

The reimbursement rate alone does not determine whether a payment receives tax-free treatment. 

Program structure, documentation, and the handling of excess reimbursements also matter.

What Counts as Business Mileage in Idaho?

Business mileage generally means driving for a legitimate business purpose rather than ordinary commuting between home and a regular workplace.

Examples can include traveling from an office to a customer location, driving between job sites during the workday, making deliveries or service calls, and traveling to certain temporary work locations.

Under federal tax rules, ordinary travel between an employee’s home and regular workplace is generally considered personal commuting. 

Different rules can apply to certain temporary work locations and qualifying home-office situations.

Clearly defining business versus personal vehicle use can help employees maintain accurate mileage records and help employers apply their reimbursement policy consistently.

What Is the Idaho State Employee Mileage Rate for 2026?

Idaho has separate mileage reimbursement rules for employees using private vehicles on official state business.

The Idaho State Board of Examiners establishes the mileage rate and travel policies that apply to state employees. 

For 2026, Idaho’s published State Travel Policy lists the private vehicle mileage rate at 70 cents per mile.

The IRS increased its business mileage rate from 70 cents to 72.5 cents beginning January 1, 2026. 

The Idaho State Controller subsequently recommended increasing Idaho’s rate to 72.5 cents per mile effective February 1. 

The State Board of Examiners ultimately left Idaho’s rate unchanged at 70 cents per mile.

Idaho’s travel policy also explains how changes to the federal rate are handled. If the federal mileage rate falls below the Idaho rate, the state rate automatically decreases to match it. 

When the federal rate rises above the state rate, the Board of Examiners reviews the change and determines whether an adjustment is appropriate.

That distinction became especially important in 2026 because the IRS increased its business mileage rate again, to 76 cents per mile, beginning July 1.

Employers and employees looking for the current official state rate should check the Idaho State Controller’s State Travel Policy.

For official state travel, mileage is generally based on the most direct or efficient route. Idaho’s policy allows commonly used mapping resources to be used to determine mileage.

The policy also addresses situations in which a state vehicle is available but an employee chooses to drive a personal vehicle for personal reasons. 

In those circumstances, reimbursement can be limited to one-half of the established mileage rate unless full reimbursement is specifically authorized and documented.

These state travel rules apply to official government travel. They do not establish a mileage reimbursement rate for private employers in Idaho.

What Is the Idaho Workers’ Compensation Mileage Reimbursement Rate for 2026?

Idaho workers’ compensation rules provide mileage reimbursement for qualifying travel related to medical care for a work-related injury or occupational disease.

According to the Idaho Industrial Commission, when an injured worker uses a private vehicle for qualifying medical travel, reimbursement is calculated at the prevailing state employee mileage rate.

Because Idaho’s currently published 2026 state mileage rate is 70 cents per mile, qualifying workers’ compensation medical mileage is reimbursed at 70 cents per mile while that remains the prevailing state employee rate.

There is also an important mileage threshold. Idaho law provides that an employee is not reimbursed for the first 15 miles of a round trip or for a round trip totaling 15 miles or less.

For example, if a qualifying round trip to medical treatment is 50 miles, the first 15 miles are excluded under the rule, leaving 35 reimbursable miles.

The Idaho Industrial Commission confirms this rule in its current benefits guidance and directs workers to the State of Idaho mileage rate for current reimbursement information.

Because the applicable state mileage rate can change, employers and injured workers should check current Industrial Commission and State Board of Examiners guidance when calculating reimbursement for a particular trip.

What Mileage Reimbursement Options Can Idaho Employers Use?

Private employers can choose among several approaches for reimbursing the real, business-required costs employees incur when using personal vehicles for work.

Cents-Per-Mile (CPM)

Cents-Per-Mile (CPM) reimburses employees using a set rate for each qualifying business mile.

Employers can use the IRS standard mileage rate or establish another appropriate rate. CPM can work well for employees who drive occasionally because reimbursement directly follows documented business mileage.

When employers want qualifying mileage reimbursements to receive tax-free treatment, applicable accountable-plan and substantiation requirements still need to be met.

Fixed and Variable Rate (FAVR)

Fixed and Variable Rate (FAVR) reimburses employees for the real, business-required fixed and variable costs associated with owning and operating personal vehicles for work.

Fixed costs can include depreciation, insurance, registration, and other ownership expenses. Variable costs can include fuel, maintenance, and tires.

Separating these cost categories allows reimbursement to reflect differences in business mileage and geographically variable vehicle expenses.

FAVR is an IRS-recognized mileage allowance methodology with specific requirements. Employers considering FAVR should make sure their program meets the applicable IRS rules for tax-free treatment.

Tax-Free Car Allowance (TFCA)

A Tax-Free Car Allowance (TFCA) is an accountable reimbursement arrangement designed around the real, business-required costs employees incur when using personal vehicles for work.

Tax-free treatment depends on meeting applicable accountable-plan requirements, including substantiating business expenses and properly handling excess reimbursements.

Companies with different types of drivers can also use a mixed mileage reimbursement strategy. 

For example, FAVR may suit employees with substantial recurring business mileage, while CPM can work for employees who drive less frequently.

How Should Idaho Employers Manage Mileage Reimbursement?

A clear mileage reimbursement policy helps employees understand which trips qualify, how mileage should be recorded, which reimbursement method applies, and when reimbursement will be paid.

Accurate mileage records also support accountable-plan requirements and give Finance, HR, and Operations teams better visibility into business driving.

Employers should review reimbursement programs regularly. Idaho is a useful example of why. 

The IRS business mileage rate increased from 70 cents in 2025 to 72.5 cents for the first half of 2026, then to 76 cents beginning July 1, while Idaho kept its state employee rate at 70 cents per mile for 2026.

Different rates can apply depending on the type of travel and reimbursement program involved, so employers should make sure their policies clearly identify which rate or reimbursement methodology they use.

Build a Mileage Reimbursement Program That Fits Your Idaho Drivers

Idaho private employers have flexibility in how they structure ordinary business mileage reimbursement. 

Federal tax requirements and Idaho’s specialized rules for state and workers’ compensation travel still make accurate records and a clear reimbursement policy important.

The right approach depends on how often employees drive, where they work, and the real, business-required costs associated with using their personal vehicles.

Cardata helps companies design and manage mileage reimbursement programs, including FAVR, CPM, TFCA, and mixed programs for different driver groups. 

From mileage capture and reimbursement calculations to compliance support and direct-to-driver payments, Cardata helps make mileage reimbursement simpler for employees and easier for Finance, HR, and Operations teams to manage.

Talk to Cardata about building a mileage reimbursement program for your Idaho drivers.