EU citizen doing consultancy visits in Germany - requirements

• Hi,
  I am an EU citizen (UK passport), I don't live permanently in Germany, but I visit here sometimes as a consultant on a project (this project is ending soon). The company I work for is based in the Cayman Islands. I never spend more than 2 weeks in Germany, usually less than that.
  
  How do the requirements affect me - for example, why should I register as a resident, if I don't really live here? The rule about registering after living in Germany for 90 days - how is that 90 days calculated, if I have only been visiting as a consultant for a short period of time? Surely the 'counter' is reset each time I arrive.
  
  I hope someone can clarify things for me.
  
  thanks
  

  21 feb 2008, 05:32 Bob