Due to uncertainty, one may become non-resident and return again. Is there a minimum number of years one must stay as non resident in order to claim it?
There’s no minimum number of years that you have to stay outside Canada to be treated as a non-resident of Canada. Non-residency is based on severing all of your primary ties and most of your secondary ties, and your intention to permanently leave. If you return to Canada after a short period of time, the CRA could argue that you never intended to permanently leave and so you will remain a tax resident of Canada.