From 1 April 2009, landlords and employers should check that anyone carrying work on gas appliances or flues is registered under the new Gas Safe Register. CORGI registration will no longer carry any statutory force. There is no grace period.
For residential property, this will be a breach of the Building Regulations 2000 but more importantly residential landlords will breach Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998 if their regular gas appliance checks are carried out by a person who is not registered on the Gas Safe Register.
In the commercial property field, the failure to check that an installer is registered under the Gas Safe Scheme may mean a breach of the Building Regulations 2000 and Regulation 3 of the Gas Safety (Installation and Use) Regulations 1998.