If you failed to declare gains from Bitcoin or other crypto assets in earlier German tax returns, you face a question with a clear answer: a voluntary disclosure that exempts you from prosecution under section 371 of the German Fiscal Code only works for as long as the offence has not been discovered and none of the statutory blocking grounds applies. That window is currently getting shorter. The German Crypto Asset Tax Transparency Act has applied since January 1, 2026, and in the 2027 calendar year crypto service providers will transmit data for the 2026 reporting period to the Federal Central Tax Office for the first time.

This article explains how a subsequent declaration works in practice, which years are still open at all, what…