May 2017: If you leave Canada, will you still be eligible for OAS? Yes, if you are at least 65 years old, a Canadian Citizen or legal resident at the time your OAS application is approved, and have resided in Canada for at least 20 years. (If not, you still may be eligible if you lived in a country with a social security agreement with Canada, or contributed to the social security system in a country with which Canada has a social security agreement.)