We are flying to Canada on the 13th of August. From my understanding, if I stay in Canada until the 12th of July 2020, I would have been out of the country for a continious peiod of 330 days, and I then become a non-resident from the day of departure (13th August 2019) as long as I dont spend more than 90 days in RSA between 12 July 2020 and 28 Feb 2021. I will still he a resident for the 2020 tax year though but only till 13th Aug 2019 so will have to file a return with things proportionally allocated.
As from 13th August 2019 I will also not be ordinarily resident in SA, as my family are leaving with me, my job, my house, schools, church will be in Canada. I have sold everything in SA, no property, resigned my job here etc.
So, 2020 will be my last tax return. Until I either meet the ordinarily residency test (ie basically move everything back) or be present for at least 91 days in any year plus the 5 preceding years.