Fuel Mix Disclosure (FMD)

What is Fuel Mix Disclosure (FMD)?

The Electricity (Fuel Mix Disclosure) Regulations 2005 (SI 2005 No. 391) introduced a requirement on all electricity suppliers in Great Britain to disclose to their customers the mix of fuels used to generate the electricity supplied annually, provided that electricity is supplied for a full disclosure period (1 April – 31 March). Suppliers must disclose this information by 1 October annually.

This regulation was introduced into electricity suppliers’ standard licence conditions (SLC), and is now SLC 21. 


Renewable Energy Guarantees of Origin certificates (REGOs) must be held in a supplier’s Renewables and CHP Register account by midday 1 July following the generation disclosure period. 

At midday on 1 July, all REGOs held in a supplier account on the Renewables and CHP Register for the relevant disclosure period that are not retired or revoked will be redeemed. Ofgem does this to capture REGOs used for GB FMD. 

EU Guarantees of Origin (GoOs) 

From the disclosure period beginning 1 April 2023 and onwards, GoOs are no longer recognised for use in GB FMD, FIT annual levelisation, or CfD.  

The 2022-23 reporting period was the last year suppliers could use EU GoOs that had been recognised by Ofgem relating to the disclosure period for FMD.  

Ofgem does not recognise Non-EU GoOs for GB FMD. 

For more information on GoOs, please see the Guarantees of Origin webpage

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