CRA considers that a return with substantial deficiencies has not been validly filed for late penalty and statute-barring purposes

Where a taxpayer files a return that is missing substantial particulars, CRA considers that the return has not been validly filed for late-filing penalty purposes (or, potentially, for purposes of the gross negligence penalty under s. 163(2).)  Furthermore, although an initial assessment of such a return would cause the normal reassessment period (of at least three years) to start running, CRA would consider that such deficiencies would permit CRA to reassess that return beyond the normal reassessment period.

Neal Armstrong.  Summary of 11 June 2014 Memo 2014-0519701I7 under s. 162(1), s. 163(2) and s. 152(4)(a)(i).