What is the impact of a mistake made by the Canada Customs and Revenue Agency on the self-assessment process?

Canada's tax system is based on the principle of self-assessment. As explained by my colleague Blais J. in Boudreault v. Canada Customs and Revenue Agency, 2002 FCT 84, at paragraph 30, while it is understandable that an individual might want to benefit from an error made by the respondent, it is nevertheless unacceptable. By failing to inform the respondent of the error, the applicant jeopardized his chances of being granted discretionary relief under subsection 220(3.1) of the Act.