Energy Company Obligation (ECO)

Energy suppliers

This page contains general information for energy suppliers interested in the Energy Company Obligation (ECO) scheme. Detailed scheme guidance documents are included in the ‘Contacts, guidance and resources’ section of our website.

Energy suppliers have legal obligations under the Energy Company Obligation (ECO) scheme if they meet the obligation threshold outlined in the table below. Under ECO3 the supplier obligation thresholds will go through four stages. Each threshold phase will contain two elements which must be met to be considered an obligated supplier:

  • Number of domestic customers
  • Amount of supply to domestic customers

Domestic customer number and supply volume thresholds for ECO3:

  3 December 2018 to 31 March 2019

1 April 2019 to 31 March 2020

1 April 2020 to 31 March 2021

1 April 2021 to 31 March 2022

Number of domestic customers >250,000 >200,000 >150,000 >150,000
Electricity supply to domestic customers 500GWh 400GWh 300GWh 300GWh
Gas supply to domestic customers 1400GWh 1100GWh 700GWh 700GWh

When do suppliers become obligated?

At specific times we will ask suppliers to provide information on their customer numbers and supply volumes. This is used to determine whether a supplier is going to be obligated for the next phase of ECO, and, if applicable, the size of their obligations.

We offer advice and assistance to all newly obligated suppliers to make sure they’re prepared to take part in the scheme.

What are suppliers’ responsibilities?

Suppliers are responsible for meeting their obligations and ensuring that they, and any members of the supply chain acting on their behalf, comply with the scheme requirements.

How are suppliers’ targets worked out?

As scheme administrator, we’re responsible for setting suppliers’ obligations. We do this using a calculation based on their share of the gas and electricity supply market. This is determined by the ECO3 Order.

Trading obligations

In 2017 the Department for Business, Energy and Industrial Strategy introduced the option for obligated suppliers to trade their obligations with other obligated energy suppliers. Our guidance page describes how suppliers should go about trading their obligations.


Under ECO3, energy suppliers will be able to deliver up to 10% of their obligation through the installation of innovative measures to eligible households. Suppliers will also be able to use a new monitored measures route to deliver up to 10% of their obligation. Our guidance describes how suppliers can deliver measures under each of the innovation routes.

The innovation routes are optional and energy suppliers do not have to deliver measures under them.

Suppliers will still be able to apply for alternative scoring methodologies where necessary.

The ECO register

Each month, obligated energy suppliers notify us of the measures they’ve delivered by uploading them to the ECO register. Contact us if you experience any problems using this, or require access.

Where do I find out more?

You can find more detailed information in the Contacts, guidance and resources section of our website. This includes our official ECO3 guidance, as well as information on ECO3 measures ECO3 Appropriate Guarantees and key templates and checklists.

The ECO reporting working group section of our website also contains key standardised ECO templates such as the Declaration of Conformity and Completed Installation and Help to heat group and Private Domestic Premises Checklist.

Publications and updates