Per diem in Horizon Europe projects: what grant holders need to know

Travel costs are one of the most common sources of ineligible expenditure in Horizon Europe audits. Not because organisations are doing anything dishonest, but because the per diem rules for EU projects are different from national rules, and many finance teams apply the wrong reference table.

If your organisation runs Horizon Europe projects and charges travel costs as actual costs, this guide explains exactly what the rules require.

The EU Commission per diem table: what it is and where it comes from

The European Commission publishes a table of Daily Subsistence Allowance (DSA) rates covering 181 countries. This table is updated at least once a year. For Horizon Europe, it's the binding reference for what you can charge as travel subsistence under a grant agreement.

The rates are set by Commission Decision and published in the Official Journal of the EU. They're also available in the annotated grant agreement templates on the Funding and Tenders portal. The table you need is the one referenced in your specific grant agreement, not the general national tables your HR department may use for internal travel policy.

That distinction matters. A Belgian NGO staff member travelling to Vienna for a consortium meeting is not subject to ONSS rates for that trip. The applicable ceiling is the Commission DSA rate for Austria, as set at the time of travel.

How the DSA ceiling works in practice

The Commission rate is a maximum, not a mandate. You can reimburse less. You cannot charge more to the project, even if your internal travel policy allows higher amounts or your national rules have a higher threshold.

The rate covers meals and incidental expenses. Accommodation is separate — the project can reimburse actual accommodation costs up to a reasonable ceiling (which is usually defined in your grant agreement or the specific call conditions).

Day trips with no overnight stay are treated differently. For a trip returning the same day, the Commission typically applies a fraction of the daily rate, depending on the hours of absence. Your grant agreement or the applicable Annotated Model Grant Agreement (AGA) specifies the exact rule for your call.

Flat rate vs. actual costs

Horizon Europe offers two approaches to travel costs: actual costs and simplified cost options, including flat rates.

Under actual costs, you claim what you spent, capped at the Commission per diem rate for subsistence. You need receipts for accommodation. You need documented proof of travel (boarding pass, ticket, mission report). And you need to show that the per diem rate you applied was the Commission rate in force on the travel date, not the rate you happened to have in a spreadsheet from last year.

Under a flat rate (if your grant agreement allows it), the per diem calculation is predetermined and agreed at project start. This removes the audit burden on individual trips but requires that the flat rate itself was correctly negotiated and that you apply it consistently. Many smaller organisations find that actual costs with proper documentation is simpler than managing a flat rate correctly.

What changes year to year

The Commission updates the DSA table periodically. The update cycle is not always January 1st. For Horizon Europe, the relevant document is usually an Annex or a Commission Decision published in the Official Journal. The Funding and Tenders portal does not always flag when the table changes, which means your project officer may not proactively notify you.

The practical risk: a project running from 2023 to 2027 will span multiple DSA updates. Applying the 2023 rate to a 2026 trip creates an ineligible cost if the rate for that destination has changed. The amount may be small per trip. Multiplied across a consortium of ten partners over four years, it can become a material finding.

Multi-country trips

This is where most finance teams get into trouble. A trip that crosses two or three countries in one day requires you to apply the DSA rate for each country separately, prorated by the hours spent in each. There's no "apply the highest rate for the whole day" shortcut.

The AGA is explicit on this point. If your colleague flies Brussels to Warsaw for a morning meeting and returns the same day, you have a Belgium departure (probably no DSA, depending on hours), a Poland rate for the time in Warsaw, and documentation to support both segments.

In practice, most consortium projects don't enforce this with that level of granularity on every trip. But an external audit will. The documentation needs to exist to justify what you charged.

What the audit trail needs to contain

An audit of Horizon Europe travel costs will typically check four things.

First, that the trip happened. This means a mission report, meeting agenda, or confirmation of attendance — something that establishes a business purpose for the travel and ties it to a specific project activity.

Second, that the dates and destination are documented. Boarding passes, hotel invoices, or conference registration confirmations work. The country and the travel date are both necessary to apply the correct DSA rate.

Third, that the per diem rate applied matches the Commission table in force on that date. A printout of the Viatic calculation or a direct reference to the Commission Decision is sufficient. An unexplained figure in a spreadsheet is not.

Fourth, that accommodation costs are backed by receipts and stay within the ceiling defined in your grant agreement.

Common mistakes

Using national rates instead of Commission rates is the most frequent error. It usually happens because the finance team applies the same logic to EU project travel that they apply to domestic missions. The rates are different and the source is different.

Applying an outdated Commission table is the second most common issue. The DSA table looks similar from year to year, and rate changes are not dramatic. But "similar" is not "the same", and an audit that picks a destination where the rate changed will find the discrepancy.

Not documenting the per diem rate source at all is the third. If your expense report shows a subsistence amount and there's no reference to the applicable Commission rate, the auditor has to verify it manually or ask you to provide the documentation retroactively. Neither outcome is good for your relationship with your project officer.

Erasmus+, ESF, and other EU programmes

Horizon Europe is not the only programme that uses Commission DSA rates. Erasmus+, ESF+, Interreg, and other EU-funded programmes generally apply the same or similar tables, though the specific provisions depend on the applicable regulation and call conditions.

If you're running multiple EU projects under different programmes, check the grant agreement for each one. The per diem rules for Erasmus+ mobility projects differ from those for collaborative research projects under Horizon Europe. They're similar enough to cause confusion and different enough to cause errors.

Current Commission DSA rates on Viatic

You can check the Commission per diem rate for any of the 208 covered countries on Viatic. The rates are sourced from the Official Journal and reviewed weekly.

• Belgium (Brussels)
• Germany
• France
• Poland
• Czech Republic
• Sweden
• Italy
• Spain
• Romania
• United States