I need to be out of Switzerland for 4 months.

I heard the limit is 3 months. Is there a exception rules? I hope they will not reject me when I come back.

Thanks.

The limit is 3 months for L Permit holders.

For B and C permits, it's 6 months

Reference:
http://www.admin.ch/ch/e/rs/142_20/a61.html

This should be a sticky, it's one of the most commonly asked questions and has a straightforward answer.

Sorry to bump this up. I might get a job outside of CH. If I do not relocate (but keep 2 households), can I keep my Swiss B permit, which expires in 3.5 yrs? What happens after the 3.5 yrs then? Do I need a job in CH in order to keep the permit, as long as I'm happy to keep an address somewhere in the country?

Keeping an address here is not enough. You also need to have a job and pay taxes, otherwise your permit won't be renewed yearly.

so that's only possible if I make a company and eventually get a contractor job abroad... and do swiss local taxes on income? (I guess that's drifting away to another set of questions).

what's the "local tax" I need to pay? Can one get a settlement with the local goverment? Or do I have to be super-rich to afford this?

Well, when OH had to renew is B permit every year he had to prove he was employed. And with a B you're taxed at source.

It's a different case, but even when you're Swiss it's forbidden to maintain an address in a canton where you don't live more than 50% of your time. Some people do it as taxes can be cheaper, but it's forbidden.

So if you maintain an address in CH you'd have to live there at least 6.1 months per year