[BjoernKW]

I suppose there are legal constructs that allow you to do this. For example, you could set up the UG mentioned above yourself and be its only employee with all the taxes and social security costs that implies.

However, that will get complicated rather quickly:

You’ll not only be that company’s sole employee you’ll also be its managing director. A managing director who owns a majority in the company usually is considered to be self-employed. A managing director also is responsible for filing annual accounts and tax statements. This is both expensive and time-consuming.

Another point to consider is that you’d effectively cover for employer’s share of the social security costs (unless they will be paying that on top of your salary, at which point they might just as well set up the UG themselves).

Not only is this a dodgy practice but you’ll also have pretty rough deal.

In any case, because this will get complicated you’d have to ask a lawyer who’s well-versed in both corporate law and social security law about the specifics.

It’d be much easier if they either were your client rather than your employer or if you were a co-founder.