Under an accountable plan (business connection, substantiation, return of excess), travel reimbursements and per diem up to the federal rate are not wages.
Per diem above the federal rate is taxable wages. It shows up in box 1, and the non-taxed portion appears in W-2 box 12 code L.
A nonaccountable plan means the whole amount is wages. (Pub 463 (2025), ch. 6, Table 6-1)
Tax-free stipends require that you are away from your tax home (see the Tax home card) on a temporary assignment (see the One-year rule card).
What it means for you
Compare each contract's weekly stipends with 7 × (GSA lodging + M&IE) for that location and fiscal year. The excess is taxable.
GSA's standard CONUS rate is the fallback. Many cities have higher rates, so check gsa.gov and record the verified rate.
First and last travel days get 75% of the M&IE.
Gray areas
Whether an agency's plan is truly accountable when it never asks for any substantiation. Ask the agency how it handles this.
"Wash" pay structures: see the Wage recharacterization card.
Stipends become taxable when
You have no tax home (itinerant), because you can't be "away from home." (Pub 463)
The assignment is, or becomes, indefinite (more than 1 year expected). (IRC §162(a); Pub 463)
The stipend exceeds the federal rate and the excess isn't returned or substantiated. The excess is box 1 wages. (Pub 463, Table 6-1)
The plan isn't accountable, for example no substantiation or no return of excess. (Pub 463, ch. 6)
Wages are "recharacterized" as per diem. See the low hourly + high stipend guide.
Duplicated living expenses
W-2 travel nurse: you can't deduct unreimbursed travel expenses on your own return, so the benefit comes only through tax-free stipends.
1099 travel contractor: you can deduct actual lodging and either actual meals or the federal M&IE rate (the standard meal allowance), with meals generally 50% deductible, plus travel to and from the assignment, on Schedule C. You must have a tax home. (Pub 463 (2025), chs. 1, 4–5)
Example From the research
Travel-stipend illustration (hypothetical, from the research). At the FY2027 standard CONUS maximum ($181/day × 7 = $1,267/week), receiving that amount tax-free instead of as taxable wages works out to an estimated ~$376/week (≈ $4,900 over a 13-week contract; estimate assuming a 22% bracket + 7.65% FICA, hypothetical). This only holds if all the tax-home conditions are met. Trade-off: lower W-2 wages mean lower Social Security earnings credited. Your numbers will differ.
Example numbers are hypothetical and come from the source research. Your situation will differ.
Common mistakes
Deducting expenses the agency already reimbursedDouble benefit, not allowedSource: Pub 463 ch. 6
Taking "travel" stipends at your tax-home area (local contract while living at home)You aren't away from homeSource: Pub 463