Easiness to justifyAverage amount deducted€ 1000-5000 per yearFrequency4-10x per year
Professional and reasonable are key words
Hotel fees must be: (i) necessary for business reasons, (ii) not to be unreasonable and (iii) If your other half travels with you, those costs are not deductible.
The daily allowances that you grant yourself during your stay abroad for professional purposes are 100% deductible.
Any restaurant costs, if clearly stated on the hotel bill, are 69% deductible for income tax and are generally not deductible for VAT.