I am copying & pasting a response from another group which I think perfectly answer this question:>>>>>>
A lot of people think that the following statement is true:
If you earned income in a year, you must file a tax return.
This is simply and outright wrong. Here is the official list:
https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/you-have-file-a-return.html
If you don't owe any taxes, you don't have to file, even if you worked. If you only have a classic T4-job, the employer will take your tax away at the source.
Of course it is always advisable to file a tax return because most people get a refund. But there is nothing wrong with not filing if you are a totally standard T4 employee.
A lot of people also think that this is true:
You must have filed three tax returns to be able to apply for citizenship.
This is, again, incorrect. You only need to be in compliance with the tax filing requirements in three years. The form asks you for two things:
Were you required to file? Did you file?
If your answer is No-No, it counts as one of those three years.
If your answer is No-Yes, it counts as one of those three years.
If your answer is Yes-Yes, it counts as one of those three years.
Only if your answer is Yes-No does it not count as one of those three years.
Source: Section 5 (1) (c) (iii) of the Citizenship Act.
Also, a lot of people think that this is true:
It is January 2019. So if you haven't filed for 2018, you can't apply for citizenship until you filed taxes if you were required to file.
This is, again, incorrect. See here:
https://www.canadavisa.com/canada-immigration-discussion-board/threads/service-annoucement-tax-filing-requirements-for-early-2019-applicants.608739/
