If the employee receives free meals from the employer, then he must reduce the amount of the meal expense proportionately, because he did not incur any additional expenses for the meals (see here for the explanation of the term additional meal expense).
The daily allowance is to be reduced by 20 percent for breakfast and by 40 percent for lunch and dinner. The basis for the reduction is in any case the larger amount of the two rates for the case of an absence of at least 24 hours per calendar day.
Example: 20 percent is to be deducted for a hotel breakfast included in the overnight stay. With the 24-euro flat rate in Germany, this means 4.80 euros. This also applies if breakfast was booked but not taken.
For lunch and dinner, a further 40 percent is to be deducted from the additional meal expenses in each case, i.e. 9.60 euros in each case.
Thus, if full board is provided, the per diem is completely reduced. In the end, the business traveler no longer has to pay for his meals, since he has been provided with breakfast, lunch and dinner.
However, this only applies if the meals are paid for by the employer. For example, anyone invited to a business dinner by a third party does not have to deduct anything.
The deductions can not become negative . Therefore, if no per diem is paid, the deduction will not affect the payment amount. On the first and last day of a trip, the reduction may not exceed the amount of the per diem for the first or last day, and thus are less than the reductions for the days within the trip.
If you get a full meal on the plane, you have to take credit for that, too. However, this only applies to real meals. Snacks such as chips, granola bars or sandwiches do not result in a reduction of the per diem meal allowance.