The Court of Justice of the EU (CJEU) has recently clarified in its important decision in VAT case C-333/20 (Berlin Chemie) the concept of a fixed establishment (FE) for VAT purposes.
A FE can be created by a another legal entity if a business can dispose staff and technical means of another entity as if they are its own.
However, the same staff and means cannot be used both to provide and receive the same services.
Source Grant Thornton
