Right now, if you haven't tapped to enter the subway, you could exit the station and reenter at a "paper transfer required" station and be count towards a transfer oppose to being charged again.
This includes Old Mills, Jane, Runnymede, High Park, Lansdowne, Dufferin, Christle, Bay, Sherbourne and most stations on the downtown U. What is stupid is they didn't reprogram the gates at Wellesley, Lawrence West and Main Street to accept transfers while the bus (streetcar) loop is closed causing people to think they are transferring but instead are getting double charged.