The JCST works on behalf of the General Medical Council (GMC) and is mandated by this body to make recommendations for the award of Certificates of Completion of Training (CCTs) and Certificates of Eligibility for Specialist Registration via a Combined Programme (CESR (CPs)). Further details on certification types can be found here.
As of January 2016 the JCST has introduced a new certification process for those whose CCT or CESR(CP) date is on or after 1 June 2016, for information on how this process works please see here. For those whose CCT or CESR(CP) date is on 31 May 2016 or earlier information on your certification process can be found here.
Information about JCST principles on early certification can be found here, and a diagram and supporting notes explaining the early certification process can be found here.