Mileage Reimbursement Laws by State: California, Illinois & Massachusetts

Mileage reimbursement rules can get complicated when employees drive their personal vehicles for work, especially when a business operates across multiple states.

Federal tax rules provide a framework for reimbursing business mileage, but state employment laws can add their own requirements. 

California, Illinois, and Massachusetts are three important examples. Each has rules that can require employers to reimburse certain employee expenses or transportation costs.

For employers with field sales teams, service technicians, healthcare workers, and other employees who drive personal vehicles for work, understanding these differences can help shape a more consistent vehicle reimbursement program.

Here’s what employers need to know about mileage reimbursement laws in California, Illinois, and Massachusetts.

Which states have specific mileage reimbursement requirements?

Several states have laws or regulations that can affect how employers reimburse business expenses or work-related transportation. 

California, Illinois, and Massachusetts are three important states for employers with employees who drive personal vehicles for work.

The details vary considerably.

California's law focuses broadly on necessary employee expenses. Illinois also has a broad employee expense reimbursement requirement, with specific rules around authorization, documentation, and employer policies. 

Massachusetts regulations address transportation expenses for employees in certain work-related travel situations.

None of these rules creates a universal state mileage rate for every private employer.

That's why employers should look at both the reimbursement method they use and the requirements in each state where employees work.

What is the California mileage reimbursement law?

California has one of the clearest employee expense reimbursement requirements.

Under California Labor Code Section 2802, employers must reimburse employees for necessary expenditures or losses incurred as a direct consequence of performing their duties.

For employees required to use personal vehicles for work, vehicle expenses can fall within that requirement.

California gives employers flexibility in how they calculate reimbursement. 

In Gattuso v. Harte-Hanks Shoppers, Inc., the California Supreme Court discussed several approaches to vehicle reimbursement, including actual-expense reimbursement, mileage reimbursement, and lump-sum reimbursement.

For employers, the important question is whether the method adequately reimburses the employee for actual and necessary business-related vehicle expenses.

The IRS mileage rate can be used as a reimbursement method, but it is not a universal California minimum or automatic safe harbor. 

If a mileage reimbursement does not fully cover an employee's actual and necessary expenses, the employer may need to make up the difference.

What is the Illinois mileage reimbursement law?

Illinois requires employers to reimburse employees for qualifying necessary expenses incurred within the scope of their employment.

Under Section 9.5 of the Illinois Wage Payment and Collection Act, employers must reimburse employees for necessary expenditures or losses incurred within the scope of employment and directly related to services performed for the employer.

The law defines necessary expenditures as reasonable expenditures or losses required in performing employment duties that primarily benefit the employer.

That can include vehicle expenses when an employer authorizes or requires an employee to use a personal vehicle for work, depending on the circumstances.

Illinois also gives employers room to establish a written expense reimbursement policy. 

Employers can use a written policy to set reasonable guidelines for reimbursable expenses, but the policy cannot be structured in a way that effectively leaves employees paying necessary work-related expenses themselves.

Documentation is important, too. 

Employees generally need to submit a necessary expense with appropriate supporting documentation within 30 calendar days after incurring it, although an employer's written policy can provide additional time.

This is an important correction from the older version of this article: the 30-day rule concerns when the employee submits the expense, rather than requiring the employer to pay every reimbursement within 30 days.

What are the mileage reimbursement rules in Massachusetts?

Massachusetts requires employers to reimburse transportation expenses in certain situations where employees are required to travel for work.

Under 454 CMR 27.04, an employee who regularly works at a fixed location and is required to report to a different location must be compensated for qualifying additional travel time and reimbursed for the associated transportation expenses.

The regulation also covers travel during the workday. 

Employees who are required or directed to travel from one place to another after the workday begins or before it ends must be compensated for that travel time and reimbursed for associated transportation expenses.

Ordinary travel between home and work is generally excluded from compensable working time under this regulation.

For employers, this means Massachusetts should not be treated as having a blanket rule that requires reimbursement for every mile an employee drives. 

The reimbursement obligation depends on the circumstances of the trip and whether the travel falls within the state's requirements.

What is the IRS mileage reimbursement rate for 2026?

The IRS standard mileage rate provides an important federal benchmark for business driving, including for employers designing Cents-Per-Mile (CPM) reimbursement programs.

There are two business mileage rates in 2026:

The IRS initially set the 2026 business mileage rate at 72.5 cents per mile. A mid-year IRS update increased it to 76 cents per mile beginning July 1 following recent increases in fuel prices.

The IRS rate is optional at the federal level. It is a standardized method for calculating vehicle costs and can also play a role in substantiating certain mileage allowances for tax purposes.

Employers should avoid treating it as a universal answer to state reimbursement requirements. California, Illinois, and Massachusetts each have their own rules to consider.

Is mileage reimbursement tax-free?

Mileage reimbursement can generally be excluded from an employee's taxable wages when the arrangement meets applicable IRS accountable plan requirements.

Under an IRS accountable plan, expenses must have a business connection, employees must adequately account for them within a reasonable period, and employees must return excess reimbursement within a reasonable period.

For a CPM program, using the IRS mileage rate alone does not automatically make payments tax-free. Employees still need to substantiate their business mileage, and the reimbursement arrangement needs to satisfy applicable accountable plan requirements.

Employers can also use other vehicle reimbursement approaches.

A Fixed and Variable Rate (FAVR) program separates projected vehicle expenses into fixed and variable costs and can account for geographic differences in vehicle expenses. 

A Tax-Free Car Allowance (TFCA) provides another approach for organizations looking to structure vehicle reimbursement around accountable plan requirements.

The right option depends on how much employees drive, where they drive, and the needs of the workforce.

How should employers manage reimbursement across multiple states?

For employers with drivers in California, Illinois, Massachusetts, and other states, consistency matters, but a single reimbursement policy still needs to account for state-specific requirements.

Start with a clear policy that defines qualifying business driving, explains how mileage should be documented, and establishes how reimbursement is calculated. 

Employers should also know where each employee works and review the rules that apply in those jurisdictions.

Accurate mileage records are especially important. They give employers visibility into business driving and help support reimbursement calculations and tax documentation.

Organizations with different driver populations can also consider a mixed program. 

For example, occasional drivers may fit well in a CPM program, while higher-mileage field employees may be better suited to FAVR. 

The goal is to match the reimbursement approach to how employees actually use their personal vehicles for work.

Managing mileage reimbursement with Cardata

State reimbursement requirements add another layer to an already detailed process. 

Employers need to keep track of business mileage, reimbursement methods, tax rules, driver documentation, and the requirements that apply in the states where employees work.

Cardata helps businesses design and manage mileage reimbursement programs for employees who use personal vehicles for work. 

Programs can include Cents-Per-Mile (CPM), Fixed and Variable Rate (FAVR), Tax-Free Car Allowance (TFCA), or a mixed approach based on different driver populations.

Book a demo with Cardata to see how Cardata can help you build a mileage reimbursement program that works across your driver population.