You cannot sublet your place if you live in subsidized housing, a superintendent's unit, or housing provided by a school where you work or are a student (such as Ryerson residence).
The RTA covers sublets in which you as the original tenant plans to return and reside in the unit before the lease expires, which indicates that there must be an agreement between the landlord and yourself as the tenant for a specific term. Therefore there cannot be a sublet for a month-to-month tenancy, but you can theoretically create a subtenancy for one month less one day.
If you do not intend to return after your subtenant moves in, this is considered a lease assignment or lease takeover which is entirely different than a subtenancy.
If you are not moving out but allow another person to live in the rental unit with you, this is not considered a sublet. Rather, the new person is considered an occupant of your rental unit who is able to live at the rental unit at your invitation. If this new person is not added to the lease, s/he is considered an occupant. Occupants a) must vacate the premises at the same time as the tenant to avoid being considered an unauthorized occupant which can lead to eviction, and b) are technically unable to sublet without written consent from the master tenant and the landlord.
TIP: We encourage you to add new people to the lease to avoid issues arising between yourself, the new occupant, and the landlord. This will certify the new person’s status as “tenant” in which they have all the rights and protections that you have under your lease and the RTA.