When you arrive at YUL, you will transit through the connections centre. This connections' area is dedicated to travellers transiting through Montreal to other destinations.
After completing the process, you will be asked to follow one of two procedures:
1- If your airline offers the option of automatically transferring your luggage and your departure flight is on the same day as your arrival flight, you will be directed to the international departure area. Please note that if you are not arriving from the European Union or the United States, you will be directed to the dedicated security checkpoint beforehand. You do not have to upload and provide your declaration in ArriveCan.
2- If your airline does not offer the option of automatically transferring your luggage or your departure flight is not on the same day as your arrival flight, you are required to download and provide all required information through ArriveCan and pass through the border control. Then, you will need to pick up your baggage from the carousel and follow the usual route for international arrivals, then follow the normal procedure for international arrivals, and then for international departures.