Under the RPZ rules, a property may qualify for an exemption if it was not let at any time during the two years before the new tenancy began. The landlord should be able to support this with evidence and must follow the required RTB notification and rent-setting rules. This exemption does not automatically apply if the property was occupied under a tenancy during that period, even if it was vacant for much of the two years. Whether the exemption is valid in a particular dispute is ultimately decided through the RTB process or by a solicitor based on the facts.