By David J. Rotfleisch ( September 23, 2026, 3:29 PM EDT) -- This is part one of a two-part series examining Siam v. Canada, 2026 FCA 91, in which the Federal Court of Appeal addressed a recurring evidentiary problem in tax reassessment litigation: what a taxpayer must actually prove when arguing that the Canada Revenue Agency never sent an original Notice of Assessment. The decision is a useful reminder to every Canadian tax lawyer that the framework governing these disputes, drawn from Mpamugo v. Canada, 2016 TCC 215, places the evidentiary burden squarely on the taxpayer, and that a credible finding against the taxpayer at the first stage of that framework can be dispositive on its own....