Length and destination of the business trip affect the amounts
Your employer is entitled to pay you per diems tax free if the destination is located more than 15 kilometres away from either your home or your main place of work. What also affects the permissible amounts of per diems is the length of your trip.
Per diem allowances for 2015
Partial per diem: €18 (trips longer than 6 hours)
Full per diem: €40 (trips longer than 10 hours)
Per diems for trips to other countries
Meal money: €10
The form of tax-exempt coverage known as 'Meal money' may be paid to employees to whom no per diem allowance is paid on business trips.