While thy Ministry has already introduced an open access clause for the BMBF project funding, journal publishing of results from projects funded by the BMBF are now to be realized in such a way that they are free available on the internet either immediately upon publication or after expiry of a maximum period of twelve months.

The additional expenses come from the BMBF´s Post-Grant Fund for open access publication expenditures. Cost of up to € 2,000 (net) will be incurred, if the contents are results of completed BMBF funded projects. If the publication expenses exceed € 2,000 (net), an additional 20% of the additional costs will be funded, which mean a total of up to € 2,400 net.

Source:
https://www.bmbf.de/de/hilfe-bei-kosten-fuer-open-access-4722.html