Benedict - Tax Court confirms the taxpayer's ability to subsequently use non-discretionary deductions which he did not fully claim when they arose

Woods J. confirmed that where a deduction in computing income (in this case, the terminal loss deduction under s. 20(16)) is mandatory ("shall be deducted") rather than elective ("there may be deducted"), the taxpayer's failure to claim the full amount of the deduction in the year it otherwise arose does not stop him from including the unclaimed amount in non-capital losses deducted by him in subsequent years.

Scott Armstrong.  Summary of Benedict v. The Queen, 2012 TCC 174 under s. 20(16).