In Brisbane, Queensland rules generally allow rent to increase only once every 12 months for a property, not simply every time a tenant changes. Your landlord must usually give at least two months’ written notice for a general tenancy, and an increase during a fixed-term lease may be restricted unless the agreement permits it. Queensland law does not set a standard maximum percentage, but you may be able to challenge an increase you believe is excessive through the RTA and, if needed, QCAT. Check the current guidance on the Residential Tenancies Authority website for your circumstances.