" Under subsection 169(4) of the ETA, a registrant may claim ITCs only if he or she provides the information required in section 3 of the Input Tax Credit Information (GST/HST) Regulations (Regulations). The GST/HST registration number is one item of prescribed information. That number is not shown on the invoice provided by the appellant, and she did no verification to determine whether the supplier was validly registered. The information required by the regulations is mandatory (Davis v. Canada,  T.C.J. No. 505(QL),  G.S.T.C. 134, 2004 TCC 662) and the requirement must be strictly enforced (Systematix Technology Consultants Inc. v. Canada,  F.C.J. No. 836 (QL),  G.S.T.C. 74, 2007 FCA 226)."
See George v. The Queen, (2014 TCC Lamarre)