Hi,
tax % does not play any role in negotiations; the taxation comparison between Geneva and Zurich is irrelevant for the company, it is only relevant to you personally. You may choose to live in Germany and commute (and pay taxes in Germany), or you may choose to live in Kanton Zug and commute (where taxes are lower).
I think you should:
- aim for the increase in your salary, since you are moving up in the carreer.
- they want you, so you are the best candidate. Hence, asking for an increase from the previous package is reasonable.
Good luck! And thanks for sharing the salary info, btw. It doesnt sound unreasonable, but I am not having enough experience in CH to assess that.
Cheers!