You can find all deadlines for previous years here: https://gvl.de/en/node/1412/distribution-distribution-plans/current-deadlines-target-dates. 
The deadline is always December 31 of the year preceding the respective final distribution. Once a final distribution has taken place, the entire budget for radio and TV extra formats has been distributed, and retroactive remuneration—and therefore also registration—is no longer possible.

Unfortunately, we can only make the most recent past year available for reporting once the stations relevant for distribution have been approved by the GVL committees and delegates. This usually happens around the middle of the following year. As usual, we will inform you as soon as a new year is available for reporting.