Per diem is not income, until it is
Per diem — the daily allowance airlines pay crew to cover meals and incidental expenses while away from base — is one of the most misunderstood pieces of a pilot's compensation. Structured correctly under IRS rules, per diem paid through an accountable plan is not taxable income at all. It is a reimbursement for a legitimate business expense, not additional pay. But "structured correctly" is doing real work in that sentence, and the edge cases catch more crew than most expect.
To qualify as non-taxable under an accountable plan, the payment generally has to satisfy three conditions: it must be for a deductible business expense, the crew member must substantiate the expense (in practice, airlines handle this through time-away-from-base records rather than individual receipts), and any amount paid in excess of substantiated expense must be returned. Most major and regional carriers structure per diem to meet these conditions, which is why per diem generally does not show up as taxable wages on a pilot's W-2.
Where the federal M&IE rate comes in
The IRS publishes federal meals and incidental expense (M&IE) per diem rates, including a special "transportation industry" rate that airlines commonly reference, updated periodically by the General Services Administration and IRS. Per diem paid at or below the applicable federal rate for time genuinely away from your tax home is treated as a reimbursement, not income. Per diem paid above that rate — which is uncommon at major carriers but has come up in disputes at some operators — can become taxable to the extent it exceeds the federal ceiling, and the excess should appear on your W-2 as wages.
The practical implication: if your per diem rate ever looks unusually generous relative to industry norms, or if your union publishes benchmarking information on per diem structure during contract negotiations, it is worth confirming with payroll how the excess, if any, is being reported — rather than assuming the entire amount is automatically tax-free.
Reserve, deadhead, and international time create real edge cases
A few specific situations generate more confusion than the baseline rule:
- Reserve days. Whether reserve time away from base generates per diem depends on your specific contract's definitions of duty and away-from-base time — this varies by carrier and is worth confirming directly against your current contract rather than assuming it mirrors a prior carrier's rules.
- Deadhead legs. Time spent deadheading (repositioning as a passenger) is treated as duty time for per diem purposes at most carriers, but the specific language governing this is contract-specific.
- International layovers. Per diem for international destinations is sometimes calculated using different published rates than domestic per diem, and currency conversion or foreign expense substantiation can add complexity — though this rarely changes the fundamental tax treatment for the crew member, since the airline, not the individual, handles the accountable-plan compliance.
What crew still need to track themselves
Because per diem paid correctly under an accountable plan is excluded from W-2 income, crew generally cannot separately deduct unreimbursed meal expenses while on trips — the Tax Cuts and Jobs Act eliminated the miscellaneous itemized deduction for unreimbursed employee business expenses through at least 2025 for most W-2 employees, a limitation worth confirming has not changed for the current tax year before assuming otherwise. What crew members should still track independently are unreimbursed costs that fall outside the per diem structure entirely — uniform maintenance, required equipment, certain training or currency costs not covered by the company — since the deductibility of those depends on your specific employment status and current tax law.
State tax treatment of per diem is not always uniform with federal treatment
Federal per diem treatment under an accountable plan is the baseline, but individual states do not always mirror federal rules precisely, and pilots domiciled in or paying tax to a state with its own distinct treatment of reimbursed employee expenses should confirm the specific state's approach rather than assuming automatic conformity. This is particularly relevant for pilots who changed domicile states mid-career, since the prior state's treatment may not match the new one, and payroll systems do not always update state-specific nuances automatically just because a federal accountable-plan structure is already in place.
Recordkeeping habits that make a per diem question easy to answer later
Because per diem is generally excluded from W-2 wages when handled correctly, most crew members never need to produce individual meal receipts to substantiate it — the airline's time-away-from-base records serve that function under the accountable plan. Still, it is worth keeping your own personal log of trip dates, layover cities, and any unusual pay events (irregular operations, extended layovers due to mechanical or weather delays) for at least the years still open to IRS examination, since discrepancies between your personal recollection and payroll's automated calculation are far easier to resolve with your own contemporaneous records than by trying to reconstruct a year-old trip sequence from memory during an inquiry.
The takeaway
Per diem's default tax treatment is favorable: money in your pocket that is not added to your taxable income, as long as your airline's payment structure stays within an accountable plan and at or below applicable federal rates. The exceptions worth watching are payments above the federal ceiling, ambiguous reserve-day and deadhead-time rules specific to your contract, and the now-limited ability to separately deduct unreimbursed expenses. When in doubt about how a specific per diem structure at your carrier is being reported, ask payroll directly rather than assuming the crew-room consensus is accurate for your contract.