The CRA has levied a tax of over 900 bucks on my OAS of CAD 5.500.

Are any of you receiving OAS and how is it taxed? Doesn't your 'personal amount' apply? 

You should "move" to a country that has a Social Security Agreement with Canada.  USA is one of those.  After "moving" you would not be subjected to any withholding but would be paying income tax in USA but none in Canada.

 

Quote from Services Canada web site:

If you live outside Canada and are not considered a Canadian resident for income tax purposes, we withhold a non-resident tax from your monthly Old Age Security payments. The tax rate is 25% unless reduced or exempted by a tax treaty between Canada and your country of residence.

 

There are ways to reduce your tax obligation on OAS, but I am not sure under what conditions that can be accomplished.  You would need to file an election under Section 216.

 

Perhaps start at:  https://www.canada.ca/en/revenue-agency/services/tax/international-non-residents/individuals-leaving-entering-canada-non-residents/non-residents-canada.html

 

Link to Canada/Thai tax treaty: https://www.canada.ca/en/department-finance/programs/tax-policy/tax-treaties/country/thailand-convention-1984.html