If you work in HK and out of Canada for more than 183 days, you only pay HK tax.
If less than that, you pay HK tax first, then pay the difference in Canada, as Canadian tax rate is higher.
But if you work in HK and out of CAnada for more than 183 days, still you need to declare non-resident first. Then no need to pay Canadian tax. But of course, need to give up care card, etc etc.
You should have no resident ties, such as, house, spouse, under 18 years kids in Canada, and you leave Canada more than 183 days, then you should be non-resident.
I already declared non-resident and has left Canada for more than 183 days, but Revenue Canada still took tax from me for full year. Can I ask for refund?
I guess either case, I will need to pay HK in full first.... sigh....