Hello.
We're holding a C permit, and we're planning to Freeze it and live in the US for severl years.
I've been told that I may need to close my Swiss bank account if I live in the US/ have a US bank account (which also means that I'll need to close my swiss mortgage).

Has anyone encounter such a situation?
Thanks!

Well, first you need to check with your bank - UBS, Credit Suisse and PostFinance are about the only ones who even allow US customers these days so maybe if you bank with them you might be able to keep things as they are now. If you don't bank with any of those then yes, you're probably going to have to close accounts and will lose your mortgage completely so would likely have to sell the property.

More importantly though talk with your commune/gemeinde about putting the permit on hold. There are reasons why it can be done, but just wanting to go live in another country for a few years doesn't sound a reason that would be accepted. Usually it's things like your employer sends you there on assignment for a few years, you're going to be studying there for a few years, etc.