I hold a valid multiple-entry B1 visa for Canada, which I have used in the past for business related travel. I am planning a tourist visit to the United States soon, and would like to transit via a Canadian airport on my way back. Would I need to obtain a separate transit visa for this purpose, or can I use my currently valid B1 visa to transit Canada?
Immigration in Canada clarifies that:
There is no separate application for business visitors. The temporary resident visa covers all visitors, including those in Canada on business.
If your business partners or contacts are likely to visit Canada a number of times, they may want a multiple entry visa. This means they will not have to request a visa every time they want to enter Canada. Multiple entry visas are granted whenever possible.
Such a visa allows you to board a flight that will connect to an onward international destination in Canada. Depending on your flight connections, you may not even need to enter Canada, and transit without visa can be accomplished at certain Canadian airports, and particularly when you hold a US visa and onward tickets to an international destination.
The Transit Without Visa (TWOV) program allows eligible foreign nationals to transit through Canada without a visa or an eTA. At present, the TWOV program operates at the Vancouver International Airport in British Columbia, Canada, the Calgary International Airport in Alberta, Canada, and Toronto's Pearson International Airport (Terminal 1 only) in Ontario, Canada.