Gas safety is a legal and practical responsibility for anyone who owns or manages a property with gas appliances. A Gas Safety Certificate (also known as a CP12) proves that gas appliances and flues have been checked by a qualified engineer and are safe to use. But how often do you need one, and who is responsible for arranging it? This guide explains how frequently a Gas Safety Certificate is required in the UK , who needs it, and why staying up to date protects both people