Double Taxation Relief Manual: Guidance by country: Canada: Offshore activities
Article 27A contains provisions for the treatment of activities in connection with the exploration or exploitation of the sea bed, sub-soil and natural resources. These provide that
a) a resident of one country carrying on such activities in the other country is deemed to be carrying on a business in that other country through a permanent establishment;
b) earnings for duties in connection with such activities performed offshore in one country may be taxed in that country.
Refer to Article 27A(3) for details of certain limitations in connection with the duration of the activities.