When working on Horizon Europe projects, costs for external experts can be declared in different ways depending on the type of contract you establish with them. These experts are most often treated as “other goods, works and services”, but two other options may also apply. Understanding which category fits best will help you avoid issues during reporting and audits.

Three Possible Cost Categories

1. Other Goods, Works and Services (C.3)

This is the most common approach. Here, the external expert is treated as a supplier providing a clearly defined service for an agreed price. Examples might include paying an expert for a specific training session, evaluation, or technical study.

2. Personnel Costs – Natural Person (A.2)

In some cases, external experts can be reported as personnel costs, but only if strict conditions are met. The contract with the consultant must resemble an employment arrangement, in particular:

• The work is carried out under conditions similar to those of an employee (organisation of tasks, working environment, etc.).
• The output of the work belongs to the beneficiary (unless agreed otherwise).

This option is less common, but it can apply if you contract an individual consultant directly rather than a company.

3. Subcontracting (B)

If an entire task within the project is outsourced to an external expert, the cost can be declared under subcontracting. The benefit here is flexibility: subcontractors are not bound by Horizon Europe’s personnel cost calculation rules, so their hourly rates may be higher than in the A.2 category. However, subcontracting must follow procurement rules, ensuring transparency, value for money, and no conflict of interest.

Key References from the Annotated Grant Agreement (AGA)

• AGA Article 6.2 – A Personnel costs
  Natural persons working under a direct contract (not employment) and seconded staff can be eligible if:
  (a) they work under conditions similar to those of an employee, and
  (b) the results of the work belong to the beneficiary.
• AGA Article 6.2 – C.3 Other goods, works and services
  Costs must be based on actual expenses incurred. This includes consumables, translations, publications, dissemination activities, and external services such as expert studies.
• AGA Article 6.2 – B Subcontracting costs
  Eligible if based on real costs, following normal purchasing practices, ensuring best value for money (or lowest price), and avoiding conflicts of interest. Contracting authorities must also respect national public procurement laws.

👉 In summary:

• Use C.3 Other goods, works and services if you’re buying a defined service.
• Use A.2 Personnel costs if the expert works under employee-like conditions.
• Use B Subcontracting if you outsource a full project task.

Correctly classifying external experts ensures compliance with Horizon Europe rules and smooth financial reporting.