Ofgem published version 3.0 of the ECO4 Delivery Guidance and Measures Table on 7 August 20251. The version contains general formatting and drafting improvements alongside specific updates1.
On hybrid heating, paragraph 5.148 was added to provide a definition for an ASHP/Gas Boiler Hybrid Post Main Heat Source1. Paragraphs 5.181 to 5.182 were updated on the claiming of compensation for boiler and heat pump installations1.
ECO4 Flex administration was revised: paragraphs 3.174 to 3.213 and Tables 3, 4 and 5 were updated to reflect administrative updates to ECO4 Flex, and paragraphs 8.7 to 8.9 were added on the ECO4 Flex audit process1. On solar PV, paragraph 5.209 was updated to include a requirement that some electricity generated must be used in the heat of the domestic premises, paragraphs 5.211 to 5.214 were added on Solar PV requirements and eligibility, paragraph 5.220 was added on battery storage installations, and paragraphs 6.123 and 6.124 were added on installing solar PV where a pre-existing system is already present1. Paragraph 6.50 notes the exemption of solar PV measures from the notification of two separate measures where the POPT for each measure notified is the proportion to the heated floor area served by each system1.
A new section entitled "RdSAP 10 Update" (paragraphs 4.25 to 4.31) was added regarding the RdSAP 10.2 update, its version requirements and its corresponding transitional period1. Paragraph 5.164 was updated to include differences in eligibility and scoring between RdSAP versions1. References to PAS 2035:2019 were updated to PAS 2035:2023 throughout1.
Other changes in version 3.0 included removal of the requirement for a full set of heating controls alongside First Time Central Heating and following a boiler installation, removal of the Council Tax band requirement for Pre-Condition 2, and removal of the requirement for a gas connection at the start of the project for on-gas homes1. Paragraph 5.4 was added regarding ineligible measures in park homes1.
The guidance has since been revised. Version 3.1 was published on 10 October 2025 and contained general formatting and drafting improvements1. Version 3.2 was published on 8 December 2025, clarifying when Ofgem will seek to reject non-compliant measures and how rural areas in Scotland are defined1. Version 4.0 was published on 26 March 2026, reflecting the extension of ECO4 by nine months to 31 December 20261. That version also confirms the Great British Insulation Scheme closed on 31 March 20261.
Why it matters for households
ECO4 is the current Energy Company Obligation scheme, under which energy suppliers fund efficiency and heating measures in homes. The version 3.0 changes touch on what can be installed and how eligibility is evidenced, including the treatment of hybrid heat pumps, solar PV and battery storage, and the assessment software used to score a property. For a household, the practical effect is that the rules an installer works to when assessing a home and specifying measures were updated on 7 August 2025, with further changes in October and December 2025 and March 2026. The later extension of ECO4 to 31 December 2026 means the scheme runs for nine months longer than previously set out1.
What happens next
Version 4.0, published 26 March 2026, reflects the extension of ECO4 to 31 December 20261. The guidance notes that Working Tax Credit and Child Tax Credit ceased to exist on 5 April 2025, and that due to the 12-month rule receipt of either remains legitimate evidence until 4 April 20261. The deadline for applications for Innovation Measures is confirmed in new paragraph 6.1601.