Use the RTB’s official Rent Pressure Zone map and designation records, keeping a copy that shows the property’s address and the relevant dates. If the boundary is unclear, ask the relevant local authority whether it can confirm the property’s status in writing. Provide supporting documents such as the tenancy agreement, rent notices, rent history and dates, since the rules and any exemptions may depend on when the tenancy or increase arose. RPZ status does not by itself prove that a rent increase was unlawful; the RTB will assess the evidence and individual facts.