Every traveler who submits an expense report eventually hits the same fork in the road: claim the per diem allowance, or track and submit actual expenses with receipts. Both are legal under U.S. federal rules, both are widely used, and both can be abused. The right choice depends on who is paying (employer or employee), how often they travel, and whether they can stomach the paperwork.
This guide compares the two methods for FY2026 travel and explains when each wins — with the exact GSA and IRS rules that govern them.
What a Per Diem Allowance Actually Is
A per diem is a fixed daily allowance an employer pays to cover lodging, meals, and incidental expenses while an employee travels away from home. Under the GSA per-locality method, the FY2026 standard CONUS rate is $178/day — $110 lodging + $68 M&IE — with higher rates for roughly 298 non-standard cities such as San Francisco ($259–$272 lodging) and New York City ($179–$342). See the full FY2026 rate table.
When an employer pays at or below the federal rate, and the employee substantiates the time, place, and business purpose of the travel, the per diem is treated as reimbursed under an accountable plan — it is not taxable wages to the employee, and the employer deducts it. (IRS Publication 463; Rev. Proc. 2019-48.)
How Actual Expense Reimbursement Works
With actual expenses, the employee keeps itemized records — hotel folios, meal receipts, and proof of payment — and the employer reimburses the real costs. Actual lodging is typically capped at the GSA lodging ceiling for the destination; meals are reimbursed at actual cost or the M&IE allowance, whichever the policy chooses.
The trade-off is obvious: actual expenses are more paperwork but more accurate; per diem is simpler but can over- or under-pay on any given trip.
Head-to-Head Comparison
| Factor | Per diem allowance | Actual expenses |
|---|---|---|
| Paperwork per trip | Minimal (dates + destination) | High (all receipts + log) |
| Payroll complexity | Low — flat daily rate | High — variable reimbursements |
| Tax treatment | Excludable if ≤ federal rate | Excludable if accountable plan rules met |
| Best for | Frequent travelers, small teams | Big-ticket or unusual trips |
| Risk | May not cover actual costs | Fraud or record-keeping failures |
When Per Diem Wins
- High-frequency travel. A salesperson on the road 15 days a month would drown in receipts. A per diem converts that to one line item.
- Simplified payroll. The IRS high-low method ($319 high / $225 low for FY2026) even removes per-city lookups.
- Predictable budgeting. Finance teams know the exact cost of a trip before it happens.
When Actual Expenses Win
- Conferences and conventions. Lodging is often above the per diem cap; actual reimbursement avoids forcing the traveler to eat the difference.
- Long assignments. Monthly hotel rates can beat the daily cap, but per diem still pays full price.
- IRS audit comfort. Receipts prove the expense; per diem relies on the accountable plan safe harbor.
Mixed Methods Are Allowed
Nothing in the rules forces an all-or-nothing choice. Many employers pay actual lodging + per diem M&IE — the most common hybrid. The IRS explicitly permits paying a per diem for meals and incidentals while reimbursing lodging at actual cost. (Rev. Proc. 2019-48, §4.04.)
Keep These Records Either Way
Whether you use per diem or actuals, an accountable plan requires the employee to substantiate: the amount, the time (dates and times of travel), the place (destination), and the business purpose. (Treas. Reg. §1.274-5T.) Use the per diem trip calculator to build a dated itinerary that satisfies all four elements.
Bottom Line
Per diem is the efficiency play; actual expenses are the precision play. Most U.S. employers use a hybrid — actual lodging up to the GSA cap plus a daily M&IE allowance. Whichever you choose, document the amount, time, place, and purpose of every trip.
Sources: GSA Per Diem Bulletin FTR 26-01 (retrieved 2026-08-19); IRS Notice 2025-54; Rev. Proc. 2019-48; IRS Pub. 463. This guide is not tax advice.