If everything goes well, my wife and I will relocate to Switzerland within few months. Our current plan is to get an appartment from Zug. At first, my wife would not be working as she is a nurse and has only basic skills in the German language.

I've been told that I will be taxed at the source (Quellensteuer) but how does this actually work in our case? Does the source tax already include both federal and cantonal taxes?

According to this document, my tax rate would only be a bit over 5%. In addition, I would pay a bit over 5 % to the retirement plan (AHV) and 1% to the unempoyment insurance (ALV). My employer will cover 100 % from UVG, KVG and BVG.

This only adds up to less than 12% and this is very hard for me to believe eventhough I've checked this from my HR department and they said that this sounds realistic. Am I missing some tax or social security fee (other than the compulsory health care insurance and home insurance)?

P.s. My first post by the way :-)

The swissnetwork.com says that:

The income tax of individuals is usually assessed based upon their tax returns. In some cases individual income taxes may be withheld at source instead (source / withholding tax). The applicable tax rates are designed to cover all federal, cantonal and municipal income taxes on the respective income.

I still don't believe it.