Taxation of clinical trial expense reimbursements for Personal Income Tax

The Dirección General de Tributos (DGT) has issued a relevant ruling regarding the tax treatment of amounts received by clinical trial participants as reimbursement for transport and accommodation expenses. The central issue lies in determining whether these amounts are subject to withholding for Personal Income Tax (IRPF).

What the DGT has ruled

The administration has clarified that the exempt per diem regime is not applicable, given that in these scenarios there is no employment relationship between the participant and the organizer. The ruling establishes the following:

• If the clinical trial organizer directly manages and pays for transport and accommodation, no income is generated for the participant.
• If the organizer reimburses amounts to the participant, these will only be exempt if it is proven that they strictly compensate for the expense incurred.
• If reimbursements are made without proving such strict compensation, or if amounts are paid for free allocation, these amounts are considered monetary income. In this case, they will be subject to IRPF and the corresponding withholding.

What it means for you

For clinical trial participants, this ruling implies that receiving money to cover travel or stays is not automatically a tax-free process. If the money received exceeds the actual and documented cost of the expense, or if a fixed amount is received without justification of the costs incurred, the Tax Agency will consider it economic gain subject to taxation.

What should be done

It is fundamental that participants maintain a rigorous record and documentation supporting every expense made. To prevent reimbursements from being treated as taxable remuneration, it is necessary to:

• Keep all invoices and receipts for transport and accommodation.
• Ensure that the reimbursed amount exactly matches the documented expense.
• Evaluate the option of having the organizer directly manage the transport and accommodation services to avoid the generation of income.

Each particular situation must be analyzed to determine the most appropriate tax treatment based on the available documentation.