Might be working for a German company - help needed

[AdieR]

As I understand it, if you're based (and resident) in the UK, your tax / NI will fall under UK rules and rates (and paid in GBP), even if its a foreign owned firm. If you're likely to be based (resident) in Germany, the tax will fall under their tax system (which also means that you'd have to have a German social security number). If you're simply visiting Munich but living here, you shouldn't need this.

As for purchasing / sub-contracting from Germany, I don't see a problem, except maybe distance if there's a problem on-site for example (how easily can they get someone over if a problem arises?).