I watched a nice youtube video by nostr:npub122pnqy3sxlnghaxarll4rywx2jy5d2vf2a52pdguzmdea4wlupesdpvsgz about how to manage the taxes. There are nice tools like CoinTracking to do that.
The point is, if you don’t declare at all, you can’t claim the losses back. And the losses are something that the government actually covers. So it’s useful to declare things every year. CoinTracking generates a nice electronic report that you can send to your Finanzamt. As far as I know it includes the total amount that you have plus your gains/losses.