In most cases, your landlord can only raise your rent by a percentage called the “guideline”.
The rent increase guideline
The guideline is set by the government. By the end of each August, the government announces the guideline for the next calendar year.
For rent increases in 2017, the guideline is 1.5%. In 2016, it was 2.0%, and in 2018 it will be 1.8%.
Your landlord must also wait 12 months between increases. And your landlord must give you a written notice at least 90 days before your rent goes up.
Above-guideline increases
Your landlord can apply to the Landlord and Tenant Board for approval to raise the rent by more than the guideline.
Exceptions
The rent increase guideline doesn’t apply to all rental units. If your unit is not covered by the guideline, your landlord can raise your rent by as much as they want. But they must still give you 90 days’ written notice and wait 12 months between increases.
Source: https://stepstojustice.ca/common-question-plus/housing-law/how-much-can-my-rent-go