There is no such thing as "Canadian health insurance" in the sense most people mean it. Health coverage in Canada is administered by each province and territory separately — Ontario's OHIP, British Columbia's MSP, Quebec's RAMQ, Alberta's AHCIP, and so on — and what happens to your coverage when you move to Portugal is a question your own province answers, not a question Canada answers as a whole.
Why "how long can I be away" has no single answer
Every provincial and territorial health plan sets its own residency requirement: broadly, you have to be physically present in the province for a minimum number of days each year, and actually resident there, to keep your coverage active. Each plan also sets its own rules on temporary absences — how long you can be out of the province, for what reasons, and what happens once you exceed that. These are provincial policy decisions, reviewed and changed by each province independently, and a rule you have heard about applying to someone who left from one province is not evidence of what applies to you leaving from another.
What actually happens once coverage lapses
If your absence exceeds what your province allows, or your province determines you are no longer resident there, provincial coverage stops responding to healthcare costs incurred outside Canada — and, depending on the province, it can also affect your ability to re-enrol immediately if you return, sometimes with a waiting period before coverage resumes. None of that is unique to moving to Portugal specifically; it is the same mechanism that applies to a Canadian moving anywhere outside the country for an extended period.
Not sure what your province's rule actually is?
Tell us which province or territory you are leaving and roughly when. We cannot answer for your provincial health ministry, but we can tell you what to arrange on the Portuguese side either way.
What this means for cover in Portugal
Whatever your provincial plan does or does not cover once you have left, it was never going to be the thing that pays a Portuguese hospital or clinic directly — even provinces with a relatively generous absence allowance are reimbursing at Canadian domestic rates after the fact, if at all, not settling directly with a foreign provider. Private health cover arranged in Portugal, or an internationally-recognised policy, is the practical route for day-to-day healthcare here regardless of what your provincial plan still technically allows. See health insurance in Portugal.
Adler & Rochefort is a commercial brand of Ownizo, Unipessoal Lda., registered with the Portuguese Insurance and Pension Funds Supervisory Authority (ASF) under no. 425591790/3. General information only, not personalised advice; confirm your own province's current absence and residency rules with its health ministry before relying on any of them.
More on this subject: Insurance for Canadians in Portugal · Health insurance in Portugal