Under the Residential Tenancy Act, do we have to give three months notice of a rent increase to people paying 30% of income for rent?

No, you do not have to give people paying a tenant rent contribution (TRC) three months notice of a change in the TRC, because their rent is limited to 30% of household income.

However, you are required to give tenants paying non-RGI rents three months notice of a change in their market rent. In addition, all tenants should be notified when market rents are increasing, in case someone currently receiving a subsidy later becomes ineligible and has to pay the market rent.