If a business trip begins on one calendar day and ends on the following calendar day without an overnight stay, the midnight rule applies.
The meal allowance is then not determined for each calendar day separately. Instead, the periods of absence on both days are added together. It is sufficient if your total business-related absence on both days is more than 8 hours. Neither day has to exceed 8 hours on its own.
If this is the case, you receive the lower meal allowance once, for the calendar day on which the greater part of the absence falls.
Example: You leave for a customer at 5:00 p.m. and are back home at 3:00 a.m. the next day. You are away for 7 hours on the first day and 3 hours on the second day. Neither day exceeds 8 hours on its own, but together it is 10 hours. You therefore receive the lower meal allowance for the first day, because that is where the greater part of the absence falls.
You can find the amounts for Germany under Meal allowances.