You took the contract three states away because the rate was right. The agency mentioned per diem. Nobody mentioned that per diem can quietly become taxable income if your assignment runs long enough — and that the IRS decides that, not your recruiter.
This trips up experienced consultants constantly, especially on extended placements or renewed SOWs that stretch a six-month gig into eighteen months. The difference between tax-free reimbursement and taxable wages can run into thousands of dollars at filing time.
Here is how per diem and travel reimbursement actually work on contract roles, what tax home means in practice, and what to document starting with your very first expense.
How Per Diem Is Typically Structured on a Contract
Per diem shows up in a few different forms depending on your engagement model:
- W-2 through a staffing firm: The firm may pay a flat daily or weekly per diem for lodging and meals, separate from your hourly wage, often under what is called an accountable plan.
- Corp-to-corp (C2C): Your own entity may bill the client or prime vendor a travel line item, or you absorb travel costs and deduct them as business expenses on your corporate return.
- 1099 independent contractor: You generally receive no separate per diem line — travel costs are yours to track and deduct on Schedule C, subject to tax home rules.
An accountable plan is the key phrase. Under IRS rules, reimbursements paid through an accountable plan are not included in your taxable wages, as long as the expenses have a business connection, you substantiate them, and you return any excess advance. Reimbursements that fail these three tests become taxable wages reported on your W-2 — a nonaccountable plan.
Ask your staffing firm directly which plan governs your per diem. If they cannot answer, that is itself useful information.
What Tax Home Means — and Why It Decides Taxability
The IRS does not care where you live. It cares where your tax home is — generally the entire city or general area of your main place of business or employment, regardless of where your family residence is. See IRS Publication 463, Travel, Gift, and Car Expenses, for the governing definition.
This matters because travel expense deductions and tax-free reimbursements are only available for travel away from your tax home on a temporary work assignment. If the placement location becomes your tax home, your lodging and meal reimbursements there stop qualifying as nontaxable travel expenses — they become compensation.
Three tax home scenarios consultants commonly face:
| Situation | Tax home location | Per diem treatment |
|---|---|---|
| Short-term contract, maintain permanent residence elsewhere, return home regularly | Your permanent residence area | Generally nontaxable if substantiated |
| No regular place of business, work travels from site to site | Often wherever you regularly live (itinerant worker rules apply) | Case-by-case, consult a CPA |
| Extended placement in one metro exceeding the one-year threshold | Shifts to the placement location | Reimbursements become taxable income |
The One-Year Rule: How a Long Placement Changes Everything
This is the trap in the headline. Under longstanding IRS guidance, including Revenue Ruling 93-86 and the discussion in Publication 463, an assignment away from your usual place of work is treated as temporary only if it is realistically expected to last — and does in fact last — one year or less.
Once an assignment is realistically expected to exceed one year, or actually does, it is treated as indefinite from the point that expectation changes. Your tax home shifts to the assignment location, and travel expenses and per diem connected to that location stop being deductible or excludable, even retroactively from the point the expectation changed.
Watch for the moment your realistic expectation changes:
- An initial six-month SOW gets extended to eighteen months total.
- A client verbally signals the role will run "as long as you want it."
- You renew for a second or third consecutive term at the same site with no planned end date.
The day you can reasonably see the assignment crossing twelve months, the clock on temporary status effectively stops working in your favor. This is squarely a facts-and-circumstances determination — exactly the kind of judgment call that belongs with a CPA familiar with contractor and multi-state travel situations, not a staffing coordinator.
Travel Reimbursement Mechanics Worth Knowing
A few operational details consultants frequently miss:
- GSA per diem rates change every fiscal year and vary by locality. Before you accept or negotiate a per diem figure, check the current table at gsa.gov/perdiem for the specific city and fiscal year — do not rely on last year's number or a recruiter's recollection.
- High-cost vs standard CONUS rates differ significantly by metro area, so the same stated "per diem" can mean very different coverage depending on the client site.
- Mileage reimbursement follows the IRS standard mileage rate, also updated annually — confirm the current rate rather than assuming the prior year's figure still applies.
- W-2 employees generally cannot deduct unreimbursed employee travel expenses on Form 2106 under current law, with narrow exceptions (Armed Forces reservists, qualified performing artists, fee-basis state officials). This makes getting the employer's reimbursement structure right even more important for W-2 consultants.
- 1099 and corp-to-corp consultants typically deduct travel costs directly on Schedule C or their corporate return, subject to the same tax home analysis.
Records to Keep From Day One
Substantiation is the second accountable-plan test, and it is where most audits of contractor travel expenses actually get decided. Start the file on your first day on site, not when a Form W-2 or 1099 arrives in January.
- Signed SOW or offer letter stating the original expected duration of the assignment.
- Any written extension, renewal, or amendment, with dates.
- A simple travel log: dates away from tax home, destination, business purpose.
- Lodging receipts and a record of nights stayed, not just a monthly total.
- Meal receipts or, if using per diem rates instead of actual costs, the GSA rate table page you relied on, saved with the date you checked it.
- Mileage log with odometer readings or app-based tracking, if you drive between home and site.
- Copies of per diem or expense reimbursement statements issued by your staffing firm, showing gross vs net and any tax withholding.
Keep these for at least three years after filing, longer if you want a cushion against an amended return or extended audit window.
When to Bring in a CPA
None of this replaces professional tax advice, and it should not. Tax home determinations are fact-specific, state tax rules layer on top of federal rules in multi-state placements, and the consequences of guessing wrong show up at filing time, not when you cash the check. If your placement is approaching the twelve-month mark, spans multiple states, or your staffing firm cannot clearly explain whether your per diem runs through an accountable plan, that is the moment to call a CPA who works with contractors.
If you want to talk through how a placement is structured before you sign the next extension, the Josh Pros LLC team is happy to walk through the engagement details with you — email contact@joshpros.com or visit https://joshpros.com.
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