CRA states that there can be a services PE in Canada during the tail end of a project which ends in the first few months of a calendar year

CRA rejected the premise of a question that referred to a situation where the conditions in Art. V, 9(b) of the Canada-U.S. Convention (respecting a services PE) are satisfied during a taxation year respecting a particular project, which continues for several months longer in the following taxation year, but with the 183-day criteria not being met in that subsequent year. CRA responded that “since paragraph 9(b) of Article V of the Convention specifies that the 183-day test applies to ‘any twelve-month period,’ that period need not correspond to the fiscal year of the taxpayer.”

CRA then provided an example where a U.S. enterprise with a calendar taxation year provides services on an ongoing basis from January 15, 20_1, to January 25 20_2, and stated that it shall be deemed to provide such services through a permanent establishment in Canada for the entire period.

Neal Armstrong. Summary of 6 October 2017 APFF Roundtable, Q.6 under Treaties – Art. 5.