According to the CBSA website:
In addition, certain permanent residents are also exempted from the three-year residency requirement.
However I couldn't find the exact list of conditions for being exempt. Does any website explain this in better detail?
The website on NEXUS from CBSA says
A Canadian or U.S. permanent resident is exempt from the three year residency rule if they meet any of the following criteria:
- Individuals serving in the American armed forces in a foreign country, or
- Individuals who are a family member of a person who is a member of the Canadian or American armed forces serving in a foreign country, or
- Individuals who are a family member of a person who is serving at a Canadian or American diplomatic mission or consular post in a foreign country.
The Canadian Forces have very recently (November 2022) relaxed the rules around the recruitment of permanent residents of Canada, I would imagine they would also be exempt soon.
There's a link given on CBP website and link on CBSA website that elaborates. "Canadian and American citizens living outside of Canada or the United States or who have recently returned to either country and have not previously been able to meet the three-year residency requirement are now eligible to apply."
In addition, if you are a permanent resident of either country and have lived in either country for more than 3 years, you might be eligible (they will need to check your background, travel history etc. to confirm this).
