An audit report (Prüfungsbericht) is a document created by a tax advisor. You might need one to renew your freelance visa.
The Prüfungsbericht must be filled and stamped by a tax advisor.1 You can’t fill it yourself. If you don’t have a tax advisor, get a Prüfungsbericht from Tax Germany.
Prüfungsbericht template (Berlin Ausländerbehörde)