CRA is only waiving penalties for late-filed principal residence dispositions for 2017 and 2016 returns
CRA has summarized the detailed filing requirements for reporting a principal residence disposition and making the designation. CRA also stated:
[T]he administrative practice stated on the CRA's website, allowing the reduction of the penalty for late-filing a principal residence designation, except in the most serious cases, has been extended [from 2016-year dispositions] to dispositions that occurred over the course of the 2017 taxation year.
Neal Armstrong. Summary of 2018 APFF Financial Strategies and Instruments Roundtable, Q.11 under s. 54 – principal residence – (c).