Can a self-employed persons class applicant already be working in Canada under a different permit?

Yes, generally, someone already working in Canada under a different work permit can still apply for permanent residence under the federal self-employed persons class, as long as they otherwise meet that class's own eligibility criteria. Current permit status and eligibility for the self-employed persons class are two separate things assessed independently, so being in Canada on another permit does not disqualify someone, and it does not automatically qualify them either.

The nuance worth understanding is that working in Canada under an unrelated permit does not, by itself, establish the "relevant experience" or the "intention and ability" that this class requires. IRCC will still look at whether the applicant's actual background — including experience gained before or during their time in Canada — meets the program's own criteria around qualifying cultural, athletic, or farm management activity, and whether their overall plans and resources support a genuine intention to become self-employed here. So someone should not assume that simply being employed in Canada under a different work permit fills that gap. Because this involves separately assessing two different sets of rules at the same time, and because both can be fact-specific, anyone in this situation should confirm how their current status and this class's requirements interact by speaking with an immigration lawyer before applying.