The taxpayer was a corporation carrying on the business of selling and distributing dental products to dentists in Canada, including local anesthetic solutions. 95% of those solutions contained “epinephrine”. Prior to May 2005, the taxpayer sold the anesthetic solutions as “taxable supplies”, meaning that it charged GST. Effective May 1, 2005, it decided to treat the solutions as “zero-rated supplies” and therefore stopped charging GST.