Per Diem: Employer Rules, Rates, and Tax Treatment

Per diem is one of the few pieces of payroll administration that makes life easier for everybody. The employee stops photographing receipts for sandwiches, and you stop checking whether a sandwich was reasonable.

What it does not do is remove recordkeeping, which is the assumption that causes almost every problem in this area. The flat rate substitutes for proving how much was spent. It does nothing about proving the trip happened, and that distinction is the whole of the compliance question.

This covers where the rates come from, the three conditions that keep the allowance out of taxable wages, the travel day rule almost everybody overpays, and whether any of it is required in the first place. I build the people and records tooling for businesses without an HR department at FirstHR, and FirstHR is an onboarding and HR platform rather than a payroll provider. This is general information, not tax advice.

What Per Diem Is

Per diem is a fixed daily amount paid to an employee travelling away from home on business, in place of reimbursing what they actually spent. The published federal rates exist so that an employer paying at or below them does not have to prove the amount of the expense at all.

The phrase away from home is doing specific work and it does not mean away from the office. It refers to travel away from the general area of the employee's main place of work, for long enough to require sleep or rest. A long day trip to a client two hours away is business travel, but it is generally not a per diem situation.

The other useful distinction is between the two forms. A full per diem covers lodging plus meals and incidentals. A meals and incidentals only per diem is common at small companies that book hotels directly, and it removes the largest and most variable component from the calculation entirely.

Is Per Diem Required by Law?

Not by federal law, and this is the question small employers most often ask first. No federal rule requires a private employer to pay per diem, to reimburse travel at all in most circumstances, or to use the federal rates if it does choose to pay something.

Two qualifications matter. Several states require employers to reimburse employees for necessary business expenses, and travel costs incurred at the employer's direction fall inside that in practice, which makes the answer state-specific rather than uniformly no. And federal contracting arrangements or collective agreements can impose their own requirements independently.

Where the Rates Come From

The General Services Administration sets per diem rates for the continental United States by locality, and they run on a federal fiscal year beginning October 1 rather than on the calendar year.

For fiscal year 2026 the standard rate covering locations without a specific listing is $178 per day: $110 for lodging and $68 for meals and incidental expenses, effective from October 1, 2025 (General Services Administration). Hundreds of individual localities carry higher rates, and destinations outside the continental United States are set by other agencies entirely.

The locality element is the part small employers most often skip, usually by picking one company-wide number. That is understandable and it costs money in both directions: overpaying against a low-rate destination creates taxable excess, and underpaying against an expensive one creates an employee who is subsidising a work trip.

The High-Low Method

Because looking up hundreds of localities is exactly the administrative burden per diem was meant to remove, the IRS publishes a simplified alternative with two rates: one for high-cost localities and one for everywhere else.

The high-cost list is published annually and changes, so a policy that names specific cities rather than referring to the current list will drift. The method also comes with a consistency requirement: an employer using it for an employee must use it for that employee for the whole year rather than switching to locality rates when they happen to be higher.

For a small business with occasional travel to a handful of cities, the high-low method is usually the right trade. For one whose people travel constantly to a single expensive location, the specific locality rate is likely to be higher and worth the lookup.

The Accountable Plan Rules

Whether a per diem is a tax-free reimbursement or additional wages turns entirely on whether it is paid under an accountable plan. Three conditions apply and they apply together (26 CFR 1.62-2).

The third condition is the one small businesses fail without realising there was a condition. An advance paid for a five-day trip that ended after three days leaves two days of excess, and a policy that never asks for it back is not an accountable plan.

The consequence of failing is disproportionate to the amount involved, which is what makes it worth attention. A non-accountable plan does not just tax the excess; it makes every payment under the arrangement taxable wages, reportable on the W-2 and subject to withholding and payroll tax on both sides.

When It Becomes Taxable

There are three distinct routes from tax-free allowance to reportable wages, and they have different consequences.

The middle row is the one to notice, because it is where the false assumption bites. Employers hear that per diem means no receipts and conclude it means no paperwork. What it means is no receipts. A dated expense report naming the destination and the business reason takes two minutes and is the difference between a tax-free allowance and wages (IRS Publication 463).

Where an amount is taxable it is treated as ordinary compensation, which means it runs through payroll like any other wage item and appears on the W-2. That is a correction rather than a catastrophe, provided it is found in the same year.

Travel Days and Provided Meals

Two adjustments apply to almost every trip and both are routinely missed, which produces a small taxable excess that recurs on every single journey.

The first is the travel day rule: the meals and incidental portion is paid at 75 percent of the applicable rate on the first and last day of travel. The reasoning is obvious once stated, since a flight arriving at 6pm does not involve a full day of meals, and the effect is that a three-day trip is paid at 75 percent, 100 percent, and 75 percent rather than at three full days.

The second is provided meals. A meal the employee did not pay for, whether a conference lunch, a hotel breakfast included in the room rate, or a dinner with a client that the business paid for directly, comes out of that day's allowance. Paying the full meals rate on a day where lunch and dinner were both provided is straightforwardly an overpayment.

Setting a Policy

A per diem policy for a small business is a page. What matters is that it answers seven questions rather than that it is long.

Where per diem sits alongside your other travel and expense rules is worth settling at the same time, and it belongs in the same document as the rest of your expense reimbursement policy rather than in a separate note nobody can find.

Where Small Employers Get This Wrong

Five patterns, and four of them produce a recurring taxable excess rather than a one-off problem.

The one that is different in kind is the third accountable plan condition. Failing to recover excess advances does not create a small taxable amount; it can characterise the whole arrangement as non-accountable, which reaches every payment made under it rather than only the unreturned portion.

There is also a distinctly small-business version of this worth naming. A flat monthly travel allowance paid to somebody regardless of whether they travelled is not a per diem at all. It is compensation, it is taxable, and calling it an allowance changes nothing about that, in the same way that a vehicle stipend paid as a flat amount is wages rather than a reimbursement (IRS Topic 511).

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