The European services directive distinguishes between the establishment of a company of a Member State of the European Union in another Member State on the one hand and of the cross-border provision of services On the other hand.
Establishment means the actual pursuit of an economic activity by a service provider for an indefinite period and through a fixed infrastructure from where the business of services actually carried out. Foreign service providers and companies must sign a trade - as well as the domestic entrepreneur -.
No Office exists in the temporary exercise of a service activity in another EU Member State. The operating headquarters are still abroad, however the company can operate temporarily commercially in Germany.