We landed in June 2013 ,we were there for less than 3 months ,due to illness of my mother in law we have to came back and she died in December ,now we are here to look after our father in law we are planning to come back in August 2016.during our stay we got our pr cards ,health cards and sin cards open our bank accounts ,kids got admissions in schools ,but could not go to schools due to summer vacations.we applied for cctb and have now returned all the overpayments.now we only have our single bank account in Canada.we are filing tax returns in our home country ,but we did not file any return in Canada.should we declare ourselves non residants to cra .and how it can be done by writing a simple letter to them from our home country.