ECO4 Flex: Local Authority Flexible Eligibility

ECO4 Flex, formally "ECO4 Flexible Eligibility", is a household referral mechanism within the wider ECO4 Scheme. It exists for homes that would not qualify for ECO4 through the benefits route: households on a low income or in a vulnerable situation who are not in receipt of the means tested benefits that would make them eligible automatically¹. Instead of a benefits check, a local authority, the Scottish Government or the Welsh Government identifies the household and issues a declaration that the supplier-funded scheme then accepts².

The practical effect is that a household with a combined gross annual income under £31,000, or with someone in the home whose health is badly affected by cold, can be referred for funded insulation and heating work without claiming any qualifying benefit². The scheme is part of ECO4, which requires medium and large energy suppliers to fund energy efficiency improvements, and which runs until 31 December 2026 following a nine-month extension³. ECO4 Flex is voluntary for councils, so whether it is open to a particular household depends first on whether its council has published a statement of intent, and second on whether a supplier has funding available at that moment. Eligibility, both Ofgem and participating councils stress, does not guarantee funding¹.

The purpose of flexible eligibility and its intended households

ECO4 Flex was designed to solve a specific problem with supplier-funded energy efficiency schemes. The main ECO4 route identifies eligible households through means tested benefits, which is administratively simple but blunt: it misses households who are poor or vulnerable without claiming those particular benefits. Flexible eligibility lets local authorities and devolved administrations use their own local knowledge to find those households and refer them into the scheme². Breckland Council describes the mechanism as allowing local authorities to identify the most vulnerable households who could benefit from energy efficiency improvements⁴.

The route is deliberately narrow in one respect: it applies only to private sector housing. Leeds City Council states this plainly, and Ofgem's delivery guidance confirms that measures delivered through Flex must go to private tenure homes, meaning owner occupied or private rented sector households⁶. Social housing is served by a separate part of ECO4. A household must also own its own home or have the permission of its landlord to benefit¹.

Two cautions belong at the front of any description of the scheme. First, participation is voluntary for councils, the Scottish Government, the Welsh Government and suppliers⁸, so coverage is uneven across the country. Second, even where a council participates and a household is declared eligible, the money is not assured. Pembrokeshire County Council reports that there is very limited funding available through the ECO4 Flex scheme and that many approved ECO providers have no access to funding at all⁹. A declaration opens a door; it does not pay for the work on its own.

For a household's energy independence, the significance is real but bounded. Funded insulation, heating and renewable measures reduce a home's running costs and its exposure to energy prices, and work such as solar photovoltaic panels can shift some generation to the home itself. But the funding comes from energy suppliers, delivered through installers and providers, and the household remains dependent on a supplier choosing to fund the project and on the installer's commercial decisions. ECO4 Flex reduces dependence on high energy use; it does not remove dependence on the scheme's own machinery.

Flex compared with the standard benefit qualification path

The main ECO4 route, often called the Help to Heat Group, works from a list of means tested benefits. If a household receives one of them and lives in an eligible property, it qualifies, and the assessment is essentially a paperwork exercise. Ofgem's eligibility form lists the routes into the scheme as the Help to Heat Group, social housing, LA Flex, in-fill and Supplier Flex¹⁰, and the distinction between them matters for how a household is actually assessed.

Under LA Flex, the benefits list is replaced by the council's own published criteria. The household is assessed against those criteria, the council issues a declaration, and the supplier can then count the measures delivered towards its obligation. The evidence burden is different too: the approved provider or agent must collect and submit evidence of income and other relevant details to the council for eligibility assessment, rather than the household simply proving a benefits award¹.

There is also a supplier-side route that sits alongside the council route. Energy suppliers can refer households under ECO4 Flex where they are either struggling with persistent fuel debt and are supported by suppliers, or are using pre-payment meters and have regularly been unable to stay connected to their fuel supplies due to financial hardship². This is distinct from the benefits route in the same way LA Flex is: it identifies hardship through supplier records rather than through the benefits system.

The two routes are not equally available to referrers. Ofgem's delivery guidance states that there are four separate qualifying routes to identify low income and vulnerable households, and that suppliers may only provide evidence for Routes 2 and 4¹¹. Councils and devolved administrations can refer under the routes that require local knowledge; suppliers are confined to the ones built on their own data. A fuller comparison of the two eligibility paths is on our page ECO4 Flex vs the Help to Heat route.

Four ways households can be referred

ECO4 Flex operates through four qualifying routes, added to the scheme's guidance as it evolved¹². A household must meet at least one of them, and the property must meet the band requirements attached to that route.

Route 1: low income. Owner occupied households in EPC bands D to G with a total combined gross annual income from all sources less than £31,000, and private rented households in bands E to G meeting the same income test¹. Essex County Council describes the test in the same terms: a household income below £31,000¹³.

Route 2: proxies. Households in EPC bands E to G, owner occupied or private rented, that meet at least two of a list of proxies reflecting indicators of low income and vulnerability¹. The combination rules are strict: proxies 1 and 3 cannot be used together, and Ofgem's guidance states that proxies 6 and 7 cannot be used in combination with one another either¹¹. Ceredigion County Council also notes that proxy 5 is unavailable in its area, which shows that individual councils can narrow the list further¹.

Route 3: health referral. Owner occupied households in bands D to G and private rented households in bands E to G, identified and referred by a GP, a Health Board or an NHS trust¹. The person's severe or long-term health condition must be due to a cardiovascular condition, a respiratory disease, limited mobility or immunosuppression⁵. Income is not taken into consideration if the household qualifies because of a health condition¹³. Ofgem provides a standard NHS referral letter, which can be used for Route 2 proxy 3 and must be used for Route 3¹¹.

Route 4: bespoke targeting. This route is applicable to ECO4 Flex only. Suppliers and local authorities can apply to the Department for Energy Security and Net Zero (DESNZ) where they have identified new methods of identifying low income and vulnerable households, demonstrating that the methodology is more effective than Routes 1 and 2⁷. For owner occupied homes in starting SAP bands D to G, all measures are eligible under Route 4; private rented homes in bands E to G must receive at least one of solid wall insulation, first time central heating, renewable heating or district heating¹⁵.

Eligible properties and required outcomes for measures

The property conditions are as important as the household conditions. Only properties in EPC band D to G can be treated under ECO4¹⁶, and the scheme sets a minimum improvement that the completed project must achieve: properties with starting EPC bands F and G must be improved to an EPC D, while properties with starting EPC bands E and D must be improved to an EPC C¹. Ofgem's delivery guidance states the same requirement, that band D and E homes must reach at least a band C and band F and G homes at least a band D⁴.

This minimum improvement rule is what makes ECO4 Flex a whole-house retrofit scheme rather than a single-measure grant. A supplier funding work through Flex is not merely paying for one item; the project must lift the property to the required band, which usually means a package of insulation and heating measures assessed together. Any measures outside of ECO4 delivered to the same property would have to be installed either before the ECO4 retrofit project was started or after the entire project is complete and all measures have been installed².

Tenure determines which bands apply. Owner occupied homes qualify in bands D to G under Routes 1, 3 and 4⁴, while private rented homes are generally held to bands E to G, the least efficient properties. This reflects the wider design of ECO4, under which suppliers must upgrade a minimum equivalent of 150,000 private tenure band E, F and G homes⁴, a target carried through from the government's original response to the ECO4 consultation⁸. The scheme's stated focus is on supporting low income and vulnerable households and improving the least energy efficient homes¹⁴.

Alongside Flex, ECO4 includes an in-fill route that lets neighbouring homes join a project anchored by an eligible property. For in-fill houses, the eligible measures are solid wall insulation and/or district heating, and the applied measure or measures must match those of the associated ECO eligible property; for in-fill flats, cavity wall insulation, solid wall insulation and district heating are eligible, again matching the anchor property. In-fill applies to any tenure and starting SAP bands D to G⁴.

Measures funded under ECO4 Flex

ECO funding pays for energy efficiency measures such as heating improvements and insulation¹⁷. The measure list published for ECO4 Flex is broad. Examples include solid wall insulation, cavity wall insulation, room in roof insulation, loft insulation, flat roof insulation, electric storage heater upgrades, first time central heating to an air source heat pump, boiler upgrades from oil, LPG and solid fuel to an air source heat pump, and solar photovoltaic panels¹. West Lindsey District Council groups the offer as insulation, boilers and central heating, and solar and renewable energy technologies¹⁸, and South Cambridshire District Council's list also includes window glazing¹⁹.

Two points about cost need to be stated firmly. First, there is no published fixed price for a Flex project: what a household pays, if anything, is determined by the provider and supplier assessing the property, and eligibility does not guarantee that funding is available¹. Second, landlords may be asked to contribute towards the costs of installed measures, depending on the circumstances of the tenant at the qualifying property¹³. A household should expect the provider to set out in writing what is funded and what, if anything, is left for the householder or landlord to pay.

All ECO4 eligible measures must be delivered to eligible domestic premises, including those delivered via LA Flex and in-fill⁴. The choice of measures is determined by the ECO provider, agent or installer based on what the property needs to reach its required band¹, which is why two similar houses can receive quite different packages.

For the household, the independence gain is the strongest of any grant scheme short of full self-generation: insulation permanently reduces the heat a home needs, a heat pump or upgraded heating reduces running costs and emissions, and solar panels shift some electricity generation to the roof. The dependence that remains is on the supplier's funding decision and on the installer's specification, and, for heat pumps and solar, on the equipment and its maintenance over the years that follow.

Statements of intent, energy suppliers and TrustMark registration

The application process runs through the council's approved providers rather than through the council directly. Households wishing to apply contact one of the council's approved ECO4 Flex providers or agents, who facilitate the application, collect the evidence of income and other relevant details, and submit it to the council for eligibility assessment¹. Birmingham City Council's statement of intent puts the starting point plainly: all potentially eligible households should apply through a Trustmark-registered or approved ECO or GBIS installer to see if they could be eligible¹⁴.

The installer standards are set by the scheme. The installations of most energy efficiency measures under ECO4 Flex must be carried out by TrustMark-registered businesses adhering to the independent Publicly Available Specification (PAS) standards¹. Ofgem's measures guidance states that all ECO4 measures except district heating must be installed by, or under the responsibility of, a person registered with TrustMark or equivalent for the measure, and lodged with TrustMark or equivalent²¹. The legal underpinning is the Electricity and Gas (Energy Company Obligation) Order 2022, as amended⁵, and 2025 legislation deems an installation to adhere to the relevant TrustMark requirements unless the measure is referred by TrustMark and the referral is not withdrawn before 1 July 2026²².

Before signing anything, a household can check practical points itself: whether the installer is Gas Safe registered to work on gas boilers, and whether planning permission or building regulations approval is needed for the work being done¹⁹. Our page on TrustMark requirements for ECO4 covers the installer rules in more detail.

Councils run their processes differently, and a few examples show the range. Bridgend County Borough Council has partnered with E.ON on the delivery of ECO4 Flex, with E.ON checking applications for the council¹⁷. West Lindsey directs interested households to its local authority partner, YES Energy Solutions¹⁸. Bristol routes applications through the Home Energy Team at the Centre for Sustainable Energy, and installers or managing agents making ECO Flex declarations must contact the Centre for Sustainable Energy and sign their Code of Conduct²³. Birmingham's current statement of intent is at version 7.0²⁵, and its earlier versions remain on the council's site marked as superseded¹⁴, which is a reminder to check the date of any statement before relying on it.

Local authority involvement and where it ends

The referrers under ECO4 Flex are local authorities and, in the scheme's terminology, Devolved Administrations: the Scottish and Welsh governments². All local authorities in England, Wales or Scotland are able to make referrals through Flex⁴. Participation is voluntary for all of them, as the government's response to the ECO4 consultation confirmed when the route was designed⁸, and suppliers and devolved administrations also have an optional role²⁶. Northern Ireland is outside the scheme: the territorial extent is England, Wales and Scotland, and Northern Ireland households are served by separate arrangements such as the Northern Ireland Sustainable Energy Programme.

The council's role is to identify and declare, not to deliver or guarantee. Under ECO4 Flex, local authorities are not liable for any claims a customer makes should they be dissatisfied with the standard of work; liability is held with the installer¹. This matters for a household deciding whether to proceed: the council's declaration confirms eligibility, but the contractual relationship for the work itself is with the installer and provider.

Each participating council publishes its criteria in a statement of intent. Birmingham City Council administers the scheme according to the Electricity and Gas (Energy Company Obligation) Order 2022 and its own published criteria²⁵, and processes personal data in accordance with UK GDPR, the Data Protection Act 2018, the council's data protection policy, the Information Commissioner's Office Data Sharing Code and DESNZ guidance²⁵. Leeds City Council assesses each applicant individually against its published criteria as set out in its statement of intent⁶. Ofgem publishes separate guidance for local authorities, the devolved administrations and suppliers⁸, and a template statement of intent exists for councils to adapt²⁷.

Ofgem, as scheme administrator on behalf of DESNZ, audits the system. Its ECO4 LA Flex audit report sets out the results of the ECO4 Flex audits, the framework, stakeholder expectations, roles and responsibilities, and actions for local authorities and suppliers²⁸. DESNZ sets ECO4 policy and legislation, and Ofgem administers the scheme on its behalf³. The council will notify Ofgem of households that declarations have been issued for via the declaration notification template¹⁴.

The Flex delivery cap of 50%

The scheme rules limit how much of a supplier's obligation can be met through Flex. Suppliers can deliver up to 50% of their obligation through Flex⁴, and the supplier administration guidance states this as a ceiling on the Home Heating Cost Reduction Obligation: suppliers can achieve no more than 50% of their HHCRO through the installation of measures under ECO4 Flexible Eligibility²⁹.

The cap matters to households because it shapes supply. Flex is the route for households the benefits system misses, so the more suppliers use it, the more low income households without benefits can be reached. But the 50% ceiling, combined with the voluntary nature of supplier participation and the uneven funding Pembrokeshire describes⁹, means Flex capacity is finite and unevenly distributed between suppliers. A household declared eligible by its council still needs a supplier with Flex funding to take the project on.

The same guidance sets other caps that frame the scheme's shape: suppliers can achieve no more than 12.5% of their obligation through the awarding of Partial Project Scores, no more than 0.5% through building fabric repair uplifts, and may deliver up to 75% of their GBIS total home heating cost reduction obligation through ECO4 projects²⁹. Innovation measures are capped at 10% of a supplier's total obligation²¹. The obligation itself is divided between obligated suppliers according to each supplier's relative share of the domestic gas and electricity market, with suppliers obligated where they supply at least 150,000 customers in the relevant qualification year²⁹. Which suppliers carry the obligation, and what each offers households, is covered on our page about obligated energy suppliers.

Timelines, documentation and scheme closure

ECO4 applies to measures installed from 1 April 2022³, and its overall obligation period runs from the commencement of the ECO4 Order on 27 July 2022 to 31 March 2026⁵. The scheme was originally due to end on 31 March 2026, with no subsequent ECO5 replacement in place at that point¹, but it has been extended by nine months and will now run until 31 December 2026³. Birmingham's earlier statement of intent, published on 1 November 2024, was framed to run until March 2026¹⁴, and its replacement extends beyond that, which is why checking the current version of a council's statement matters.

Declarations have their own time limits. A declaration must be issued within the 12 month period preceding the day on which the project or measure is completed, and a project is valid so long as it starts within one year of the declaration being issued⁵. Installation extensions are granted on a per measure basis⁵.

Records outlive the scheme. Evidence of eligibility is expected to be retained for up to three years following the end of the scheme⁴, and applications and declarations may be subject to Ofgem audits during the time ECO4 is in effect and up to three years after the schemes end¹. Households approved for work should therefore keep their own copies of declarations, specifications and warranties well beyond the installation date.

What happens after 31 December 2026 is the open question. ECO4's successor arrangements were not settled when the original end date passed¹, and households planning work should treat the remaining scheme window as finite: a declaration issued late in 2026 must still lead to a completed project within its validity period. For the wider picture of what replaces or follows ECO4, see our overview of home energy grants and schemes, and for the scheme Flex sits inside, our page on ECO4.