If a tenant terminates a tenancy before the end of the rental term, the tenant is not required to find a new tenant for the rental unit. The landlord is obligated to mitigate their losses from the early termination and re-rent the unit as soon as possible.  As of September 1, 2021, landlords can file an application for loss of rent that the landlord incurred with the LTB up to one year after the tenant moves out of the rental unit. The tenant must have moved out of the rental unit on or after September 1, 2021. However, in order to file this application with the LTB, you will have to find out their new residential address to be able to serve them. The prescribed form is available on the LTB website at https://tribunalsontario.ca/ltb/forms/