My income is zero does the conditional you mention remain trickier after this point reinstated?
I don't think I minced words:
this is NOT a reliable forum for sorting out tax issues. Really. No matter how confidently an answer about a tax question is answered in this forum,
IT SHOULD NOT BE TRUSTED . . . unless you can find and verify that answer in an official or authoritative source, in which event that is not relying on what was posted here.
Or the answer is obvious. That is, sure, some questions are easy: living in Canada and employed, yeah, obligated to file a return. (Believe it or not, in the past this and similar forums have been host to rather heated dispute regarding this, more than a few zealously advocating no obligation to file a return if one's employer has withheld and paid to CRA all the taxes the individual might owe; not how it works. Just a sample of how far off this forum can be regarding tax matters.)
As for what is tricky, obviously things are a lot trickier for some and not so much for some others. It is relative. Among the factors are the individual's own experience, background, knowledge, and so on. As well as all the variable circumstances in the individual case.
Here's the rub: if it is simply about a null return, no income, no tax obligation, no credits, no benefits, no offsets, no losses, no carry-over, and so on, then it makes no sense for a non-resident to file a return if the non-resident otherwise has no obligation to file a return. As soon as any of those things is implicated, it gets more complicated. And of course for anyone resident or potentially a "deemed" resident for tax purposes, or anyone with a spouse or dependent who is a resident or potentially a "deemed" resident, or potentially obligated otherwise to file a return as a non-resident, one or more of these things is implicated.
That is taxes can be a lot more complex than simply accounting for earned income.
Those of us who do our own taxes generally rely a great deal on building a knowledge base related to our own personal situations.
For example, I believe I have figured out how to do my returns, including the requirements, including nuances and the nooks and crannies, for myself, after having been self-employed most of the last FIFTY years (I am an old man and been around the block a few times), and having solely engaged in precisely the same business I am now for a full TWO decades, including filing Canadian returns since migrating my business to Canada well over a decade ago. This or that changes from year to year, but so far the changes (such as moving my business to Canada) have not required me to go too far beyond my personal knowledge base, about MY OWN tax filings (which I have had to do in multiple countries for some time now), which I have built up over the years. An occasional professional consultation here and there (and some years in the past I have relied entirely on a professional accountant), along with help from the software company I now use, and of course the CRA information, has enabled me to adapt and keep up . . .
that is what I HOPE, anyway, but a big part of this depends on the nature of what I do and my business. In later life I have managed to keep things fairly simple. That said, if I had to start from scratch doing a tax return, even as simple as I have kept things it would be a lot more tangled than I dare sort out, so I would be back as a client with a professional without hesitation, crying a bit about the fees, while understanding big odds I'd be crying a lot more if didn't.
That said, I also do my spouse's tax return. But it is very simple. One employer. Specific retirement income sources. Simply structured investments. No dependents. No special circumstances. Same same year after year, only the numbers change. Out-of-the-box software program suffices. Not always easily, but within a range we can figure out.
. . . but a key thing I have learned along the way is that reliable tax advice is very difficult to come by. Even from professionals. As difficult as it can be to find and hire a good lawyer, it can be that difficult times three to find a competent and reliable tax professional. The good ones are mostly fully employed, not looking for new clients (note: they too rely a great deal on building up a knowledge base regarding the particular clients they service). The least reliable sources of information about tax filings tend to be those who are most confident they know what they are talking about. And maybe they do. Within the very limited scope of precisely what they are talking about, with little regard for all the many tangents that can complicate things for others.
Did I mention it is best to NOT rely on suggestions about tax matters in this forum? I think I did.
NOTE: by "professional" I do not mean those doing tax returns in mall cubicles, using their brand-name employer's software. I mean real, licensed accountants specializing in tax accounting.