A landlord may require a tenant to pay a rent deposit with respect to a tenancy if the landlord does so on or before entering into the tenancy agreement:

• the amount shall not be more than the cost of one month's rent or one rent period

  • whichever is the lesser of the two

• a new landlord of a rental unit shall not require a tenant to pay a rent deposit if the tenant has already paid a deposit

• a landlord shall pay interest to the tenant annually on the amount of the rent deposit at a rate equal to the guideline determined at the time that the payment is due

Ont Residential Tenancy Act Pt. VII s.106