Nick Broughton of Capital-GES answered this enquiry.
“If you are working in Germany on a contract for any period of time it’s not legal to use your UK limited company unless it’s registered in Germany (which I’m guessing it’s not). From day one you should be paying tax and social security in Germany. Your options to do this are to be self-employed (register your UK limited company or become a Freiberufler/German freelancer) or fully employed through an international payroll company that is registered in Germany. It’s my suggestion that you seek legal advice or contact us as we can help your situation.
“The source of the work doesn’t matter. If you are in Germany you must pay tax and social security in Germany. You cannot use a UK limited company.”