All gasfitting carried out from 1 July 2013 requires certification. Once your gasfitting is connected, the person responsible for the work has to issue a Gas Safety Certificate (GSC) that indicates the gas installation or part installation is safe to use and the gasfitting work has not adversely affected any other part of the gas installation. This is supported by Certificates of Compliance (CoCs) for any gasfitting defined as high-risk or general risk.