The difference between accountable and nonaccountable reimbursement plans comes down to tax treatment: an accountable plan pays employees back tax-free, while a nonaccountable plan turns the same payment into taxable wages. The IRS decides which category a plan falls into based on three requirements in the regulations, not on what the employer calls the arrangement. Since 2025, employees can no longer deduct unreimbursed business expenses, so a poorly structured plan hits workers harder than it used to.
The Three Tests for an Accountable Plan
An accountable plan must satisfy three requirements under Internal Revenue Code Section 62(c) and Treasury Regulation 1.62-2. Miss one, and the entire payment shifts to nonaccountable status.
Business Connection
Every reimbursed expense has to relate directly to the employee’s work and be the kind of cost that would qualify as a deductible business expense under general tax principles. Travel to a client site, project supplies, and a hotel during an out-of-town assignment all clear this bar. A personal purchase run through an expense report does not.
Adequate Substantiation
Employees have to document each expense with the amount, date, location, and business purpose. Receipts are required for any individual expense of $75 or more, and for all lodging costs regardless of amount.1Internal Revenue Service. Revenue Ruling 2003-106 Below $75, a written log capturing the same details is enough. The IRS treats substantiation provided within 60 days of when the expense was paid or incurred as timely under a safe harbor.2GovInfo. 26 CFR 1.62-2 – Reimbursements and Other Expense Allowance Arrangements
Return of Excess Amounts
If the employer advances money or pays more than the employee actually spent, the difference has to come back. The safe harbor is 120 days after the expense was paid or incurred. An alternative method lets employers send quarterly statements showing unsubstantiated amounts, giving the employee 120 days from the statement date to either document the cost or return the money. Any advance must be paid within 30 days of when the expense is expected to be incurred to stay inside the safe harbor.2GovInfo. 26 CFR 1.62-2 – Reimbursements and Other Expense Allowance Arrangements
How Each Type Is Taxed
Reimbursements that satisfy all three requirements stay off the W-2 entirely. They are excluded from gross income and are not subject to federal income tax withholding, Social Security tax, Medicare tax, or FUTA.3eCFR. 26 CFR 1.62-2 – Reimbursements and Other Expense Allowance Arrangements The employee gets the full amount back with no payroll tax haircut. The employer deducts the payments as ordinary business expenses.
Payments under a nonaccountable plan are treated as supplemental wages. The employer includes them in the employee’s gross income, reports them in Box 1 of Form W-2, and withholds federal income tax, Social Security tax at 6.2%, and Medicare tax at 1.45%.4Internal Revenue Service. Topic No. 751 – Social Security and Medicare Withholding Rates The employer also owes its matching payroll tax share plus FUTA on the amounts.
The practical effect on a worker is direct. An employee reimbursed $5,000 for legitimate business costs through a nonaccountable plan pays income tax and payroll tax on that $5,000 as if it were a bonus. The same $5,000 through an accountable plan is tax-free.
Common Ways a Plan Turns Nonaccountable
Flat allowances are the most common trap. A fixed $500 monthly car stipend, a set phone allowance, or a flat per diem paid without any requirement to document actual expenses is nonaccountable from the start.5Internal Revenue Service. Publication 463 – Travel, Gift, and Car Expenses Because the employer isn’t requiring substantiation, the arrangement fails automatically. It doesn’t matter whether the employee actually spent the money on business costs. This catches small businesses off guard because a monthly car allowance feels like a reimbursement, but without mileage logs it’s just wages with a different label.
Per diem payments above the federal rate trigger nonaccountable treatment on the excess. If an employer pays $350 per day for travel to a high-cost city where the federal rate is $319, the extra $31 per day is nonaccountable unless the employee returns it or substantiates the higher cost with receipts.
The third pattern is a plan that starts accountable but breaks down in practice. Employees who never turn in documentation, or who never return the unspent portion of an advance, cause those amounts to convert to nonaccountable payments once the reasonable period expires.
2026 Rates That Accountable Plans Rely On
Accountable plans often use IRS-approved standard rates instead of collecting receipts for every mile or every meal. Reimburse at or below the rate, and the payment stays tax-free without itemized documentation of the underlying cost.
Standard Mileage Rate
The 2026 business standard mileage rate is 72.5 cents per mile.6Internal Revenue Service. 2026 Standard Mileage Rates Employees still have to log the date, destination, business purpose, and total miles for each trip. The rate substitutes for tracking actual gas, maintenance, and depreciation, but without a mileage log the reimbursement fails the substantiation test regardless of the amount.
Per Diem Rates
Under the IRS high-low simplified method for travel within the continental United States, the 2026 per diem rates are:
- High-cost localities: $319 per day, with $86 allocated to meals and incidental expenses
- All other localities: $225 per day, with $74 allocated to meals and incidental expenses7Internal Revenue Service. Notice 2025-54 – 2025-2026 Special Per Diem Rates
Employers paying per diem at or below these rates only need records showing the time, place, and business purpose of the travel. Individual meal receipts aren’t required. Anything above the federal rate has to be substantiated with actual receipts or returned, or it becomes taxable income.
What It Costs to Get It Wrong
When the IRS reclassifies an accountable plan as nonaccountable during an audit, the employer owes the full amount of employment taxes it should have withheld and deposited, regardless of whether it collected anything from the employee’s pay. On top of the back taxes, the IRS assesses failure-to-deposit penalties that escalate with time:
- 1 to 5 days late: 2% of the unpaid deposit
- 6 to 15 days late: 5% of the unpaid deposit
- More than 15 days late: 10% of the unpaid deposit
- After an IRS notice demanding payment: 15% of the unpaid deposit8Internal Revenue Service. Failure to Deposit Penalty
Tax-exempt organizations face an additional risk. The IRS can treat nonaccountable reimbursements as automatic excess benefit transactions under IRC 4958, regardless of whether the recipient’s total compensation was otherwise reasonable. That exposes the recipient to a 25% excise tax, and if the transaction isn’t corrected, a second tax of 200%.9Internal Revenue Service. Automatic Excess Benefit Transactions Under IRC 4958 Nonprofit executives and board members should treat substantiation as non-negotiable for that reason alone.
Why This Matters More After 2025
Before 2018, employees stuck with a nonaccountable plan had a partial safety valve. They could deduct unreimbursed business expenses as a miscellaneous itemized deduction, subject to a 2% of adjusted gross income floor. The Tax Cuts and Jobs Act suspended that deduction through 2025, and the One Big Beautiful Bill Act passed in 2025 made the suspension permanent.10Nolo. Can You Deduct Unreimbursed Job Expenses There is no expiration date on this change.
For workers who travel heavily or drive personal vehicles for work, the annual difference between the two plan types can easily reach four figures. Any employer whose reimbursement policy hasn’t been reviewed since 2017 has good reason to look at the structure now, because the escape hatch employees used to have is closed for good.