Apply for non-resident of Canada

There is no trouble, since you left Canada more than 5 years ago.

There is no requirement for you to declare to be non-resident. If you really want to, you can file 'Determination of Individual Resident Status' form with CRA to get them to say you have not been resident for the past five years.

Under Canadian tax law, with few exceptions, if you do not live in Canada for more than 183 days in a given year and you do not keep resident tides in Canada, i.e. keep a home, you are not a Canadian resident for tax purpose, and you do not have to pay tax for income earned outside of Canada.

If you don't want Canadian government to check anything, the simplest thing to do is to cancel you provincial health insurance, thus saying that you are no longer living in Canada.

Unlike US, Canada only tax resident, and do not tax citizen or former permanent resident, so you have nothing to worry about.

>will it be trouble?
no, no. You won't be in trouble.
>But If I apply now, will they check back my working record and tax me for it?
Certainly, Revenue Canada will ask you to report all the income for all those years. Not filing income tax return doesn't mean you don't have to pay taxes. You have to pay back all the taxes plus interests for the last 5 years.

好有可能!

這是我個人體法!