Incidental expenses, in IRS terms, are a narrow set of small travel costs: tips and fees for porters, baggage carriers, bellhops, and hotel staff; transportation between your lodging and the places you eat; and mailing costs for travel vouchers or employer charge card payments. That’s the whole category. The incidental portion of the federal per diem is fixed at $5 a day, which is a fair signal of how small these charges are supposed to be.1Internal Revenue Service. 2025-2026 Special Per Diem Rates – Notice 2025-54
What Actually Counts
IRS Publication 463 limits incidental expenses to three things:
- Tips and fees paid to porters, baggage carriers, bellhops, hotel housekeepers, stewards on ships, and hotel servants in foreign countries.
- Transportation between your hotel or work site and a place to eat, when suitable meals can be obtained at your temporary duty location.
- Postage for mailing travel vouchers and paying employer-sponsored charge card bills while on the road.2Internal Revenue Service. Publication 463 – Travel, Gift, and Car Expenses
If a cost doesn’t fit one of those three descriptions, it is not an incidental expense for tax purposes, no matter how small the dollar amount.
What People Think Is Incidental But Isn’t
The everyday meaning of “incidental” is just “minor,” so travelers tend to sweep every small charge into this bucket. The IRS doesn’t.
Laundry, dry cleaning, and pressing of clothing are not incidental expenses. They are deductible travel costs, but the IRS treats them separately.2Internal Revenue Service. Publication 463 – Travel, Gift, and Car Expenses Telephone calls and other communication costs sit outside the definition too, even though business calls on the road are deductible on their own.3Internal Revenue Service. Topic No. 511, Business Travel Expenses
Lodging taxes are excluded. So are the larger expenses you’d expect: airfare, train tickets, rental cars, lodging itself, and meals. Each is its own deductible category with separate rules. Parking fees, tolls, and baggage shipping are also deductible as travel expenses, but none of them count as incidentals.3Internal Revenue Service. Topic No. 511, Business Travel Expenses
Why this matters: if your employer pays per diem, the $5 incidental allowance covers only the items in the IRS definition. A $3 tip to a bellhop is covered. A $12 airport parking charge is not — it needs its own reimbursement or its own receipt.
The $5 Per Diem and How It’s Paid
The incidental definition exists mostly to support the per diem system. Rather than collecting receipts for every meal and tip, employers can pay a flat daily allowance that bundles meals and incidentals together. That combined figure is the Meals and Incidental Expenses rate, or M&IE.
The General Services Administration sets M&IE rates for the continental United States, and the Department of Defense sets them for Alaska, Hawaii, and U.S. territories. Rates vary by location, but the incidental portion is always $5. The remainder is allocated to meals.4General Services Administration. M&IE Breakdowns
When an employer uses an M&IE per diem, you don’t have to track or substantiate individual meal and incidental charges. You only need to document the dates, location, and business purpose of the trip itself.
When Meals Are Provided
If your meals are covered by someone else, say a conference with catered meals or a client who picks up dinner, you can’t claim the full M&IE amount for those days. But the incidental piece still applies. The IRS sets an incidentals-only rate of $5 per day for both domestic and international travel, so your tips and other qualifying small costs are still covered without receipts.1Internal Revenue Service. 2025-2026 Special Per Diem Rates – Notice 2025-54
First and Last Day
The M&IE rate pays at 75% on the first and last calendar day of a trip, and also for any trip lasting more than 12 hours but less than 24. Full travel days in between pay 100%. The reduction applies to the whole M&IE amount, including the incidental share.5eCFR. 41 CFR Part 301-11 – Subsistence Expenses
Receipts and Records
If you’re tracking actual expenses rather than claiming per diem, the IRS requires a receipt or other documentary evidence for any lodging charge and for any other single expense of $75 or more.6eCFR. 26 CFR 1.274-5 – Substantiation Requirements Most incidentals come in well below that threshold, so you won’t usually need a physical receipt for a $5 tip or a $3 shuttle gratuity.
You still need a written record made at or near the time of the expense, showing the date, amount, place, and business purpose. A line in a travel log or a note on your phone is enough. The IRS accepts electronic records — photos of receipts, scanned documents, digital logs — as long as the images stay legible and the system maintains an audit trail.7Internal Revenue Service. Revenue Procedure 97-22
If you lose a receipt for a larger expense, bank or credit card statements can serve as backup, but an auditor has discretion to disallow a deduction if the documentation can’t be reconstructed.
Can You Deduct Incidentals Yourself?
The answer depends entirely on how you file.
W-2 employees cannot deduct unreimbursed travel incidentals on a personal return. The Tax Cuts and Jobs Act of 2017 eliminated the deduction for unreimbursed employee business expenses starting in 2018, and that suspension was later made permanent. If your employer doesn’t reimburse the costs or offer a per diem, those tips come out of your pocket with no tax benefit. It’s worth asking whether your employer uses a per diem arrangement, since even the $5-a-day incidentals-only rate removes the need to absorb those small charges.
Self-employed filers are not affected by that restriction. On Schedule C, you can deduct business travel expenses, incidentals included, either at actual cost or using the per diem method for meals and incidentals. Lodging is the one piece that always has to be deducted at actual cost with supporting documentation; you cannot use per diem for lodging as a self-employed traveler.2Internal Revenue Service. Publication 463 – Travel, Gift, and Car Expenses The incidentals-only rate of $5 per day is available to self-employed travelers on the same terms as employees, so if meals are provided you can still claim the $5 daily incidental allowance without individual receipts.1Internal Revenue Service. 2025-2026 Special Per Diem Rates – Notice 2025-54 Pick one method per trip and stay with it.