VAT identification number is not required for reverse charge procedure in accordance with Section 13b UStG
Recipient must be sufficiently identifiable for verification of identity and entrepreneurial status
§ Section 13b UStG does not require the service recipient to have or use a VAT identification number
Source: datenbank.nwb.de
Note that this post was (partially) written with the help of AI. It is always useful to review the original source material, and where needed to obtain (local) advice from a specialist.