You need to provide an EPC whenever a home* in the social or private rented sector is let to a new tenant.
You must make the EPC available free of charge to prospective tenants at the earliest opportunity. This should be when they are first given written information about the property or view it, and before any rental contract is entered into.
EPCs are valid for 10 years and can be reused as many times as required within that period. It is not necessary to commission a new EPC each time there is a change of tenant although landlords may commission EPCs for these properties at any time to prepare for a change in tenant.
If a newer EPC has been produced for a home within the ten year period, only the most recent one is valid.
The EPC provides prospective tenants with information about how energy efficient a property is that they are considering renting.
An EPC is not required for any property that was occupied before 1 October 2008 and which continues to be occupied after that date by the same tenant.
You can find more information here 
