How do I know if an Ofgem letter about insulation is genuine?

The single most useful test is this: Ofgem states that ECO is not a grant scheme, and that different companies or installers may provide different levels or types of support². A letter that presents insulation as fully funded, automatic, or already approved is describing something the scheme does not promise. Eligibility for ECO does not necessarily mean an energy supplier or installer will decide to install measures³.

Timing matters as much as wording. Applications for the Great British Insulation Scheme have now closed⁴, and the service to check eligibility for free or cheaper home insulation has closed⁵. The Energy Company Obligation is due to end on 31 December 2026, and councils or suppliers may stop taking applications sooner. A letter arriving now that invites a fresh application to a closed scheme is a strong warning sign.

Why a letter about insulation arrives at all

The Energy Company Obligation started in 2013 and requires energy suppliers to fund heating and insulation measures⁸. It is paid for through the supplier obligation, which is recovered through energy bills, not through a household application to government. That structure explains why letters come from suppliers and installers rather than from a single national body, and why the same household can be contacted by more than one company.

Ofgem's role is administrative. It sets out procedures for administering the Great British Insulation Scheme⁹, and it is described in government's own impact assessment as the scheme administrator, with delivery measured by Ofgem¹⁰. Suppliers must provide Ofgem with information on projects delivered under the scheme¹¹. Local authorities that operate flexible eligibility notify Ofgem of households for which declarations have been issued, using a declaration notification template¹².

That reporting relationship is narrow. It is not a general licence for a supplier to hand a household's details to whichever installer then writes to them. A letter that claims Ofgem has passed details to a named company is making a claim about a data flow that the published rules do not describe.

What the schemes fund is broad. ECO4 covers insulation, boilers and central heating, and solar and renewable energy technologies¹³, and ECO funding covers insulation such as loft, roofs and walls¹⁴. One restriction is worth knowing because it contradicts many letters: ECO4 will not provide for loft or cavity wall insulation on their own³.

What a genuine ECO letter can and cannot promise

A genuine letter can tell a household that measures may be available, that a survey is needed, and that support levels vary. It cannot promise a specific outcome before assessment, because the scheme rules do not work that way.

Ofgem's own wording is the clearest guide: "ECO is not a grant scheme and as such, different companies or installers may provide different levels or types of support"². Two households on the same street can therefore be offered different packages, or nothing at all. The Derbyshire County Council guidance states the position directly: "eligibility for ECO doesn't necessarily mean that an energy supplier or installer will decide to install energy efficiency measures"³.

There is also a compliance layer that a genuine letter will not misrepresent. Government consulted on updating the wording in the ECO order to clarify Ofgem's ability to reject non-compliant measures, without changing the definition of compliance¹⁵. In other words, an installer's involvement is not the same as an approved installation, and measures can be rejected after the fact.

For a household, the practical consequence is that a letter is an opening, not a decision. Nothing about the scheme removes the need to read what is being offered, who is offering it, and what the household is being asked to sign or pay.

The signs of a fake Ofgem or insulation letter

Several features of the genuine process are hard to fake convincingly, and their absence is informative.

Ofgem verifies the identity of the individual confirming consent¹⁶. Where a property is owned by an organisation, a Letter of Authorisation tells Ofgem the name of the person authorised to provide property owner consent on behalf of the organisation which owns the property¹⁶. A letter that asks a householder to confirm consent without any identity check, or that treats a doorstep signature as sufficient, is not following that process.

Ofgem also commissions audits. A statistical audit report summarises the results of a randomised sample of audits, commissioned by Ofgem, to understand the extent of issues with solid wall insulation installed under ECO4 and GBIS¹⁷. A letter that claims all installations are inspected and guaranteed as a result is overstating a sampling process.

Other markers to weigh: a demand for payment before any survey; a request for bank details, card details or a deposit; pressure to sign on the doorstep; a claim that the scheme is about to close today; and a phone number or email address that does not match the ones Ofgem publishes. Ofgem's published contact addresses are scheme-specific, including GBIS.enquiry@ofgem.gov.uk for Great British Insulation Scheme enquiries⁷ and laflex@ofgem.gov.uk for local authority flexible eligibility compliance, declarations, notifications and statements of intent.

How to check a letter before you respond

Checking takes a few minutes and does not require contacting anyone named on the letter.

1. Identify which scheme the letter names. ECO and GBIS are separate, with separate published guidance and separate contact addresses⁷.
2. Look up the contact address on the Ofgem website rather than using the one printed on the letter. Boiler Upgrade Scheme enquiries, for example, go to BUS.Enquiry@ofgem.gov.uk¹⁹.
3. Check whether the scheme is open. GBIS applications have closed⁴, and the eligibility checking service has closed⁵.
4. Check the installer's claimed role against the rules. Suppliers report project information to Ofgem¹¹; that is not the same as Ofgem endorsing a company.
5. If the letter concerns poor quality wall insulation already installed, note that Ofgem is sending letters to all affected properties setting out next steps¹. Those letters follow a known remediation process rather than offering new work.

Where a household wants to confirm a scheme position, the published enquiry routes are the reliable ones. Ofgem's Boiler Upgrade Scheme guidance gives BUS.Enquiry@ofgem.gov.uk¹⁹, and the Great British Insulation Scheme pages give GBIS.enquiry@ofgem.gov.uk⁷. Consultation and policy correspondence uses different addresses again, such as smartmetering@ofgem.gov.uk for responses to the smart metering consultation²⁰, which shows how specific these routes are.

The scheme is closing: what that means for letters arriving now

The window for new work is narrowing, and letters that ignore that are suspect.

Applications for the Great British Insulation Scheme have now closed⁴. The service to check if you are eligible for free or cheaper home insulation has closed⁵. Cheshire West and Chester Council records that the scheme ended on 31 March 2026 for new applications²¹. The Energy Company Obligation is due to end on 31 December 2026, and councils or suppliers may stop taking applications sooner.

There is a Welsh dimension. The Welsh Government has issued a written statement on support for householders impacted by the closure of the Energy Company Obligation scheme²². Where a household in Wales is contacted about ECO work, the closure position set out by the Welsh Government is the relevant official statement.

Reporting is also changing. Ofgem intends to add the Great British Insulation Scheme to its supplier performance reporting²³, which means delivery under the scheme will be visible in published data rather than only in company claims.

For a household, the practical reading is straightforward. A letter dated now that offers a new application to GBIS is offering something that has closed. A letter about ECO work may still relate to an existing project, a remediation, or a complaint, and those are different propositions from a fresh installation.

If you have already responded: your next steps

Having replied to a letter is not the same as having lost anything, but the steps taken next matter.

If the letter concerned poor quality wall insulation, the remediation route is established. Ofgem is sending letters to all affected properties setting out next steps¹, and government publishes guidance on what to do if you have poor quality wall insulation¹⁴. Householders dissatisfied with ECO installations carried out by installers other than CES should follow the standard ECO complaints process set out on the Ofgem website²². Complaints about insulation installed under the Great British Insulation Scheme follow the Ofgem energy company obligation complaints guidance⁵.

If money has changed hands or bank details have been given, report it. Suspected fraud can be reported by emailing counterfraud@ofgem.gov.uk or by calling 0207 901 7373⁶. The same address appears in Boiler Upgrade Scheme guidance for reporting suspected fraud or misuse²⁴. Ofgem will verify the identity of the individual confirming consent¹⁶, so a genuine process has an identity check at its centre.

On billing, Ofgem's back billing rules apply where a customer has not been told what they needed to pay through a statement of account before. That is the framework for disputed charges, and it is the opposite of an unexpected upfront demand.

For wider context on how these schemes have performed and what remediation looks like, see the ECO4 and GBIS insulation failures and insulation scams and cold calling. Households weighing what insulation does for independence from suppliers and the grid can read insulation and energy independence, and those checking what is still open can read closed insulation schemes.