FAQ n.19348

For business travel including an overnight stay, EASA will charge a "per diem" rate to cover all expenses of the traveller at the place of assignment, including accommodation, meals, local travel and sundry expenses. The ‘per diem’ is charged for each overnight stay during the mission (e.g. 3 nights of accommodation = 3x "per diem" charged).

The standard "per diem" rates are defined and published regularly by the European Commission, the amount varies based on the country of travel.