okay I see.The authorities in the other jurisdiction (e.g., Montenegro, as in your example) will cooperate with Switzerland.
See Sections 25–26 of the DTA.
It’s probably smarter to shut down the company before officially leaving the country, and just gradually reduce the income over time, like it’s done everywhere else.
You can easily start that process a year in advance and keep it going for a while after you’ve moved, slowly using up the retained earnings. Businesses shut down all the time for all kinds of reasons, maybe the market change, maybe you lost interest, maybe the product just isn’t profitable anymore. That’s totally normal.
As long as the timeline looks organic and the numbers make sense, nobody’s going to ask too many questions.