Per Diems: The simple rule that became a complex problem

Per Diems

Per diems are the amounts companies pay employees to cover extraordinary expenses, primarily meals and accommodation, incurred while working away from their usual place of work.

Not every company implements them. Those that do typically reach that decision for one of three reasons:

1. Travel volume reaches a point where inconsistent treatment becomes a real problem and fairness demands a clear policy;
2. A sales or field team that travels frequently sees per diems as a meaningful complement to their base salary;
3. An audit or financial review uncovers inconsistencies in how expenses have been reimbursed, and formalisation becomes necessary.

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How Per Diems Are Calculated

Tax authorities define exemption thresholds for per diem payments, the ceiling below which no income tax applies. But that ceiling is a starting point, not a rulebook.

Each company sets its own rules, based on its needs and the profile of its workforce. Some differentiate by salary band. Others vary rates by country or continent. Some cover weekends; others don't. And with each layer of customisation, a simple rule becomes a complex operational problem. This is where most finance teams lose time, money, and peace of mind.

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The Manual Process

In most companies, per diem calculation starts the same way: a spreadsheet built years ago, maintained by one person who knows exactly where the formulas live and why that column exists.

It works, until it doesn't.

Every exception to the general rules becomes a new column. An employee travelling to one country has a different rate than one going to another. A director's allowance differs from an associate's. A weekend trip may or may not be covered, depending on who approves it. Departure and arrival times determine whether meals and accommodation are paid separately or as a flat daily rate. Not every night needs to be covered, because the company booked one of the hotels directly.

Each of these variables is manageable in isolation. Together, they form a fragile system, dependent on one person, with no automatic validation against legal exemption limits.

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The Real Cost

Time

Manual per diem calculation isn't a one-off task, it's recurring, monthly, and scales with the number of employees who travel. Every request means manually checking destination, dates, seniority level, and cross-referencing it all against the internal rules table. For teams with meaningful travel volume, this adds up to tens of hours each month in manual, low-value work.

Tax Risk

When calculation is manual, the risk of applying the wrong rule, or exceeding the exemption threshold without reporting it correctly, grows with every exception added to the sheet. A recurring error, even a small one, multiplied across dozens of employees and 12 months, represents real tax exposure. And in an audit, "it was a formula error" is not a valid defence.

Employee Experience

A per diem request that should be instant sits pending because the person who owns the spreadsheet is on holiday, or because there's uncertainty about which rule applies to that specific case. The delay creates unnecessary friction and employees lose confidence in their own company's processes.

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What Changes When the Process Is Automated

Automation doesn't eliminate the complexity of the rules, it eliminates the risk of applying them manually.

Instead of a spreadsheet with formulas accumulated over years, the company configures its rules once, directly in the platform: by geography, by salary band, by departure and arrival time, with or without weekend coverage, with or without proof of expense. From there, every per diem request is calculated automatically, based on the rules already in place. No manual intervention, no dependency on one specific person, no margin for formula error.

The outcome addresses all three costs directly: less finance team time spent on manual validation, lower risk of tax exposure from incorrect rule application, and employees who receive the correct amount without waiting on human confirmation.

The complexity of per diem rules isn't going away, they'll keep varying by company, by level, by geography. The question is whether your team keeps managing that complexity manually, or lets the system do it instead.

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