Per Diem and Expense Reimbursement: Taxable?
Per diem and expense reimbursements are tax-free under an accountable plan. See what turns them into taxable wages, and what that costs in payroll tax.
WorkLogs44
Payroll Calculator
Run your own payroll numbers as you read
WorkLogs44 shows net pay and employer cost side by side.
Free · No sign-up needed
This article is for general information, not tax or legal advice. Federal per diem rates change every fiscal year, and whether an arrangement is accountable turns on the specific facts of how you pay and document it. Verify current figures with the IRS and GSA, or talk to a payroll professional before you run the check.
You just cut a $1,500 travel check. Does it go through payroll or not?
A per diem or expense reimbursement stays out of taxable wages if it is paid under an accountable plan and does not exceed the federal per diem rate for that location. The money never touches the W-2, and nothing is withheld from it.
Everything else is wages, with all the machinery that implies: federal income tax withholding, Social Security, Medicare, the employer’s matching share, FUTA, and SUTA. Where the line sits, and what it costs when you land on the wrong side of it, is the whole topic.
The line: accountable plan, or wages
“Reimbursement” is not a tax category. The plan is.
Calling a payment a reimbursement, a per diem, an allowance, or an advance changes nothing about its tax treatment. What matters is whether the arrangement it was paid under meets the accountable plan rules in 26 CFR 1.62-2. If it does, 26 CFR 1.62-2(c)(4) excludes the payment from the employee’s gross income. If it does not, the payment is compensation.
| Accountable plan, at or below federal rate | Non-accountable plan, or excess over the rate |
|---|---|
| Excluded from gross income | Included in gross income |
| Generally not reported on the W-2 | Reported in Boxes 1, 3, and 5 |
| No income tax withholding | Income tax withholding applies |
| No Social Security or Medicare | Social Security and Medicare on both sides |
| No effect on FUTA or SUTA wage bases | Adds to both wage bases |
The regulation is blunt about the failure case. Under 26 CFR 1.62-2(c)(5), amounts paid under a non-accountable plan “are included in the employee’s gross income, must be reported as wages or other compensation on the employee’s Form W-2, and are subject to withholding and payment of employment taxes.”
There is no partial credit. An arrangement that satisfies two of the three requirements is non-accountable for that payment, and the full amount is wages.
The three accountable plan requirements
Every accountable plan has to clear the same three bars.
Business connection. The expense has to be a deductible business expense the employee paid or incurred while performing services for you. A payment made whether or not the employee travels, or whether or not any expense exists, fails this one immediately.
Substantiation. The employee has to document the amount, time, place, and business purpose of the expense within a reasonable period. For a per diem paid at or below the federal rate, the amount is deemed substantiated. The employee still has to prove time, place, and business purpose, but nobody needs receipts for every meal.
Return of excess. Anything advanced above the substantiated amount has to come back to you. Let employees keep the unspent portion of an advance and the arrangement fails.
The safe harbor as a calendar
“Reasonable period” sounds like an argument waiting to happen. It isn’t, because 26 CFR 1.62-2(g)(2)(i) gives you a fixed-date safe harbor with three real deadlines:
- 30 days. An advance can be paid no more than 30 days before the expense is paid or incurred.
- 60 days. The employee substantiates the expense within 60 days after it is paid or incurred.
- 120 days. Any excess advance comes back within 120 days after the expense is paid or incurred.
Most write-ups cite 60 and 120 and quietly drop the 30. That leading leg is where flat monthly allowances fail, because money paid on the first of every month is not paid within 30 days of a specific expense.
An alternative exists. Under the periodic statement method, you give employees a statement of unsubstantiated amounts at least quarterly, and they substantiate or repay within 120 days of that statement. Pick one method, write it into your expense policy, and enforce the dates.
Federal per diem rates and what paying above them costs
For federal fiscal year 2026, which covers travel from October 1, 2025 through September 30, 2026, the GSA standard CONUS per diem rate is $178 per day: $110 for lodging plus $68 for meals and incidental expenses. GSA held FY2026 level with FY2025. Travel on or after October 1, 2026 uses the FY2027 rates, so check the fiscal year before you copy a number into a policy.
Several hundred high-cost localities carry higher rates, looked up by city and county on GSA’s per diem tool. Standard practice is to prorate the M&IE portion to 75% on the first and last day of travel.
If per-city lookups are more bookkeeping than you want, IRS Notice 2025-54 offers the high-low substantiation method for travel on or after October 1, 2025 and through September 30, 2026: $319 per day for high-cost localities ($233 lodging, $86 M&IE) and $225 per day for everywhere else in CONUS ($151 lodging, $74 M&IE). A locality is high-cost if its federal per diem rate is $272 or more. The same notice sets the transportation industry special M&IE rate at $80 CONUS and $86 outside CONUS, and the incidental-expenses-only rate at $5 per day.
Now the mechanic that matters most, and the one other write-ups tend to blur.
Paying above the federal rate makes only the excess taxable. Pay $200 a day where the federal rate is $178, collect proper substantiation of time, place, and business purpose, and $178 a day still rides free. The $22 a day of overage is wages.
Failing an accountable plan requirement makes the entire payment taxable. Pay that same $200 a day with no expense report at all, and the wages are the whole $200 a day rather than the $22.
Those two failure modes are nowhere near the same size. Get the distinction wrong and you underreport by an order of magnitude.
What a taxable reimbursement actually does to the payroll run
Most articles stop at “it becomes taxable income” and leave you to guess at the rest. Every line it touches:
Federal income tax withholding. Added to a regular paycheck, the taxable amount withholds at the employee’s normal W-4 rate along with everything else. Cut as a separate check, it is supplemental wages, and you can use the flat 22% rate on the first $1,000,000 of supplemental wages for the year, with 37% on anything above that. Either way, see how federal withholding is calculated for the underlying mechanics.
Social Security. 6.2% withheld from the employee and 6.2% matched by the employer, on wages up to the 2026 Social Security wage base of $184,500. An employee already past that base for the year owes nothing more on this line.
Medicare. 1.45% from the employee and 1.45% from the employer, with no cap at all. Once the employee’s year-to-date wages with you cross $200,000, you also withhold the 0.9% Additional Medicare Tax, and filing status plays no part in that trigger. The employee squares up on their return against a filing-status threshold of $200,000 single, $250,000 married filing jointly, or $125,000 married filing separately. There is no employer match on the 0.9%.
FUTA. Federal unemployment tax at 6.0% less the standard 5.4% state credit, for an effective 0.6% on the first $7,000 of each employee’s annual wages. When the employee has not yet hit $7,000 for the year, a taxable reimbursement eats part of that base.
SUTA. Your state unemployment rate applied to your state’s wage base, which varies widely by state, industry, and claims history.
State and local income tax withholding. Most states follow the federal accountable plan treatment, so a taxable reimbursement is taxable there too.
A worked example
Riley travels 10 days to a standard-rate city. You pay a flat $200 per day travel allowance, $2,000 total, and never ask for an expense report.
No substantiation requirement means no accountable plan, so the taxable amount is the entire $2,000 rather than the $220 above the federal rate.
- Employee: $2,000 added to Box 1, plus $124.00 in Social Security (6.2%) and $29.00 in Medicare (1.45%).
- Employer: $124.00 Social Security match, $29.00 Medicare match, plus FUTA and SUTA on whatever part of the $2,000 still falls under those wage bases.
That is $306.00 in combined FICA on a trip that should have generated zero, before you count income tax withholding or unemployment tax. The employer FICA match half of it is pure new cost to the business, and the FUTA and SUTA wage base those dollars consume is base you no longer have available later in the year.
Run the same trip correctly and the cost disappears. You pay the FY2026 standard rate of $178 per day, $1,780 for the trip before the 75% first-and-last-day M&IE proration, collect an expense report inside 60 days, and take back anything unspent. Nothing hits the W-2 and nobody pays the $306.
Scaled across a crew of ten field techs, that arithmetic stops being a rounding error. It feeds the same calculation that drives the true cost of an employee, just triggered by a check you thought was tax-free.
Modeling it by hand is where mistakes creep in, especially mid-year when someone is near a wage base cap. WorkLogs44 lets you flag a reimbursement entry as taxable or non-taxable and run it through a full payroll for the whole team, tracking each person’s year-to-date FICA, FUTA, and SUTA earnings so the caps truncate on the right dollar. If you only need the business-side number, the employer cost calculator will do that piece on its own.
How it lands on the W-2 and the pay stub
Three outcomes, depending on how the payment was made.
Accountable, at or below the federal rate, fully substantiated. Nothing appears on the W-2. The money was never gross income, so there is no box for it.
Accountable, but the allowance exceeded the substantiated amount. The substantiated portion goes in Box 12 with Code L, which is informational and not income. The excess goes in Boxes 1, 3, and 5 as wages, with withholding and both FICA sides applied.
Non-accountable. The whole payment goes in Boxes 1, 3, and 5. No Box 12 Code L, because nothing was substantiated.
On the pay stub the difference is easy to spot once you know what to look for. A non-taxable reimbursement shows up as a separate line that raises net pay without moving gross pay or any tax line. A taxable one appears as an earnings line that raises gross and pushes every tax line beneath it upward. If an employee asks why their travel money shrank, walk them through how to read a pay stub and show them which column it landed in.
Five ways employers accidentally create taxable wages
Almost every failure in practice is one of these.
- A flat monthly travel or car allowance with no expense report. Paid whether or not the employee travels, with nothing to substantiate. It fails business connection, substantiation, and the 30-day advance rule at once. The full allowance is wages.
- Letting employees keep the unspent portion of an advance. You advanced $1,000, they spent $700, and nobody asked for the $300 back. Return of excess fails, and the arrangement is non-accountable.
- Missing the 60-day substantiation window. A batch of expense reports that sits in someone’s inbox until the quarter closes can push past the safe harbor. The expense was legitimate; the timing made it wages.
- Paying above the federal rate without splitting the excess. The federal-rate portion is fine. The overage is wages and has to run through payroll, which means tracking two amounts per trip rather than one.
- The one-year rule. IRS Publication 463 treats an assignment as temporary only when it is realistically expected to last one year or less. Once the assignment is expected to run longer, that location becomes the employee’s tax home, and travel payments there are wages rather than reimbursements. Construction, consulting, and travel nursing hit this constantly, and the trigger is the expectation rather than the calendar.
One more to file away: per diem paid to an employee who owns more than 10% of the business, or to a self-employed person, can only cover meals and incidental expenses. Lodging has to be substantiated with actual receipts.
None of this is exotic. You need a written expense policy with three dates in it, an expense report requirement with teeth, and a payroll system that knows which reimbursements are taxable. Getting it wrong is one of the more expensive entries on the list of common payroll mistakes, largely because it stays invisible until an audit or a corrected W-2 makes it visible.
WorkLogs44
Payroll Calculator
See the full cost of each paycheck
WorkLogs44 works out the employee's taxes and take-home pay, then adds FUTA, SUTA and any other employer costs.
Free · No sign-up needed
Frequently Asked Questions
Is per diem taxable income?
No, as long as it is paid under an accountable plan and does not exceed the federal per diem rate for that location. It is excluded from gross income and does not appear as wages on your W-2. It becomes taxable the moment the arrangement fails an accountable plan requirement, or to the extent it exceeds the federal rate.
What are the three accountable plan requirements?
Business connection, substantiation, and return of excess. The expense must have a business purpose, the employee must document the amount, time, place, and business purpose, and any advance above the substantiated amount must be paid back. Missing one makes the arrangement non-accountable for that payment.
How long do employees have to submit expense reports?
Under the IRS fixed-date safe harbor in 26 CFR 1.62-2(g)(2)(i), an advance can be paid up to 30 days before the expense, expenses must be substantiated within 60 days after they are paid or incurred, and any excess must be returned within 120 days after the expense is paid or incurred.
Is per diem above the federal rate taxable?
Only the excess is. The portion up to the federal per diem rate stays non-taxable as long as time, place, and business purpose are substantiated. The amount above the federal rate is added to wages and is subject to income tax withholding, Social Security, and Medicare.
Is a flat monthly car or travel allowance taxable?
Generally yes. A flat allowance paid regardless of actual expenses, with no expense report and no requirement to return the unspent portion, fails both the substantiation and return-of-excess tests. Under 26 CFR 1.62-2(c)(5) that makes it a non-accountable plan, so the entire allowance is wages, not just the portion above the federal rate.
Where does per diem show up on a W-2?
Often nowhere. A per diem that is fully substantiated and at or below the federal rate is excluded from gross income and generally is not reported on the W-2 at all. Box 12 Code L comes into play when the allowance exceeds the substantiated amount: the substantiated portion goes in Box 12 with Code L as information only, and the excess goes in Boxes 1, 3, and 5 as taxable wages. Everything paid under a non-accountable plan lands in Boxes 1, 3, and 5.
What is the federal per diem rate for 2026?
For federal fiscal year 2026, which runs October 1, 2025 through September 30, 2026, the standard CONUS rate is $178 per day, made up of $110 for lodging and $68 for meals and incidental expenses. Several hundred high-cost localities have higher rates, which you look up by city on the GSA site. Travel on or after October 1, 2026 uses the FY2027 rates.
Do employers pay payroll taxes on taxable reimbursements?
Yes. Once a reimbursement is treated as wages, the employer owes its 6.2% Social Security match and 1.45% Medicare match on it, and the amount also counts toward that employee's FUTA and state unemployment wage bases. A reimbursement that fails the accountable plan rules costs the employer real money, not just the employee.