Rent increase rules vary between Australian states and territories, and can depend on whether you have a fixed-term or periodic agreement. Check the written notice, the required notice period, how often rent can be increased and whether your agreement permits the change. If the increase seems invalid or excessive, contact your state or territory’s residential tenancies authority for guidance and ask about dispute options. Keep paying the current rent by the due date while you check the rules, rather than withholding payment without advice.