An EPC is valid for 10 years from the date it is issued. A new EPC is not required each time there is a change in tenancy, or when the property is sold, as long as the EPC is no more than ten years old.
An owner, landlord or tenant can commission a new EPC within the ten year period which will then replace the earlier EPC and become the current EPC for that property.
Once an EPC reaches the ten year expiry date, there is no automatic requirement for a new one to be commissioned. A further EPC is only needed when a 'trigger point' is reached. A 'trigger point' can be when the property is next sold, let to a new tenant or substantially modified.
As the EPC relates to the property, rather than the owner, it will remain valid even after the property is sold on to a new owner, as long as it is less than ten years old.