If you let a property with gas appliances, a Gas Safe registered engineer must check them at least every 12 months. Keep each gas safety record (CP12) for at least 2 years, and give your tenants a copy within 28 days of the check, or before new tenants move in. These duties come from regulation 36 of the Gas Safety (Installation and Use) Regulations 1998 , which applies in England, Wales and Scotland.