Hill Fai Investments – Tax Court of Canada decision indicates that the record retention period for tax basis information does not start running until the last claim for that basis is made

Subject to other more specific rules, s. 230(4) requires a taxpayer to keep books and records until the expiration of six years from the end of the last taxation year to which they "relate." The six-year period starts running from the end of the year in which the relevant claim was made rather than from when the relevant cost arose so that, for example, if the taxpayer (as in this case) had claimed a bad debt deduction under s. 50, the six-year period starts running from the end of the year for which the claim is made rather than the year the advance in question was made.

This of course means that documentation supporting tax basis may have to be retained for decades.

Neal Armstrong. Summary of Hill Fai Investments Ltd. v. The Queen, 2015 TCC 167 under s. 230(4).