There can be only one CDM co-ordinator at any one time, but this can be changed throughout the life of the project. The client has to make sure the appointment is changed or renewed, as necessary, so that there is at all times a CDM co-ordinator until the end of the construction phase.
Where there is more than one client for a project, they should agree on the appointment of the CDM co-ordinator, unless they have elected one of the clients to act as sole client under regulation 8. The sole client then appoints an individual or company to act as CDM co-ordinator and fulfil the co-ordination function described in regulations 20 and 21.