Crypto Exchange Self-Certification: No Answer by 1 January 2027 and Trading Stops

Anyone who opened a crypto account before 2026 will hear from their exchange over the coming months. What it asks for is a tax self-certification: your country of tax residence, your tax identification number, and a confirmation that the details are correct. Ignore it and you do not lose your balance, but you do lose the ability to trade with it. That is what the German Crypto Asset Tax Transparency Act, the KStTG for short, lays down, and the cut-off date is 1 January 2027. German coverage of the new reporting duty is almost entirely about what the tax office will learn about you. That is one half of it. The other half asks something of you, and the consequence is not a query from the tax office but an account you can no longer trade on. This article explains the obligation, its deadlines, its consequences, and what we measured on 17 August 2026 about how providers communicate it in public. Crypto Exchange Self-Certification: What the KStTG Requires From You The KStTG transposes the EU directive DAC8 and the OECD's CARF standard into German law. It obliges crypto-asset service providers to identify their users for tax purposes and to report certain transactions once a year to the ...