Do I need to declare foreign bank accounts when I move to Switzerland?
Yes. If you become a Swiss tax resident, you generally need to declare your worldwide income and worldwide assets in your Swiss tax return. This includes foreign bank accounts, investment portfolios, securities and real estate held outside Switzerland. Declaring foreign assets does not automatically mean they will be taxed in Switzerland, but they must usually be reported.

Dear taxum,
I could not help but wonder… when you move to Switzerland, do your bank accounts abroad become a long-distance relationship?
Short answer: no.
If you are a Swiss tax resident, you declare your worldwide income and worldwide assets - including foreign bank accounts, securities, and property.
Yes, even that account you rarely log into.
Because once you are resident here, your financial life does not politely stop at the border.
And neither does the tax submission.