ECO4 is the version of the Energy Company Obligation that has been running since 2022, and for many lower-income households it is still the most realistic route to help with the cost of new windows. The picture changed in early 2026, though. The scheme was given a nine-month extension and the government confirmed it will not be replaced, so the window to apply is now firmly closing. This page explains what ECO4 is, who qualifies, what it actually covers for glazing, how to apply and what happens once it ends. If you do not qualify, our grants hub covers the other 2026 schemes, and our uPVC window calculator shows what the work would cost you privately.
What ECO4 is
ECO4 stands for the fourth phase of the Energy Company Obligation. It is a supplier-funded scheme, which means the money does not come from general taxation. Instead, larger energy companies are obligated, under rules set and policed by Ofgem, to pay for energy-saving measures in qualifying homes. Obligated suppliers include British Gas, EDF, E.ON, Ovo, Scottish Power and Utility Warehouse, and you do not have to be a customer of any of them to benefit.
The scheme is deliberately targeted at the least efficient, hardest to heat homes, lived in by households on lower incomes. Glazing is one of several fabric measures it can support, alongside insulation and heating upgrades. To put its scale in context, around 949,800 measures have been installed in roughly 280,100 households under ECO4. That is significant, but set against every household in the country it is a reminder that this is help for a minority, not a universal entitlement.
Crucially, ECO4 was extended in early 2026. It now runs to 31 December 2026, where the previous end date was 31 March 2026, and the government confirmed at the November 2025 Budget that there will be no successor supplier obligation after it. You can read the detail in our news report on ECO4 being extended to December 2026. The headline for homeowners is simple: if you are eligible, this is a scheme to use before it closes.
Who qualifies for ECO4
ECO4 is means-tested. The main route in is through income-related benefits, so a household is generally eligible if someone living there receives one of the following:
- Universal Credit
- Pension Credit Guarantee Credit
- Housing Benefit
- Income-based Jobseeker's Allowance (JSA) or Employment and Support Allowance (ESA)
- Income Support
- Child Benefit (within the relevant income thresholds)
- Tax Credits
Receiving a benefit makes you eligible to be considered, but it does not on its own guarantee that glazing will be funded for your specific home. The assessment also looks at the property itself. Because ECO4 can fund up to 100% of a measure, with a contribution sometimes required, the survey decides which measures give the best energy improvement for the money available.
There is also a second door in. LA Flex, short for Local Authority Flexibility, lets local councils help fuel-poor households that do not meet every standard ECO4 criterion. If your income is low and your home is expensive to heat but you do not tick one of the benefit boxes above, it is worth asking your council whether it runs an LA Flex scheme. To sense-check your own situation across all the live schemes in a couple of minutes, use our grant eligibility checker.
What ECO4 covers for windows
ECO4 can pay towards replacing single glazing with energy-efficient double glazing as part of a wider upgrade to the home. It is important to understand that ECO4 funds glazing as one measure within a package designed to improve the property's overall energy rating, rather than as a standalone window job you choose from a brochure. The assessor decides which measures qualify, and in many homes insulation or heating will be prioritised over windows because they deliver a bigger efficiency gain per pound.
Where glazing is approved, the scheme can cover up to 100% of that measure, though a contribution is sometimes required depending on the supplier, the home and the wider package. Treat any promise of completely free windows with caution until it is confirmed in writing. If you want to understand what makes a window energy-efficient in the first place, our guide to U-values explained covers the ratings that matter, and our uPVC window calculator gives you a realistic private price to compare against.
I have surveyed plenty of homes where the householder expected new windows and the assessment came back with loft and cavity insulation instead. That is not a stitch-up, it is the scheme doing its job: the funding follows the biggest energy saving. Take whatever ECO4 offers, and never sign for windows on the back of a grant nobody has actually confirmed in writing.
Tom Bradley, FENSA-registered installer
How to apply for ECO4
The single most important point is that you cannot apply to ECO4 yourself. There is no central application form for homeowners. Instead you apply through a participating installer, who works on behalf of an obligated supplier and arranges a home assessment. The broad process runs like this:
- Check your eligibility. Confirm someone in the household receives a qualifying benefit, or ask your council about LA Flex if you are fuel-poor but do not quite meet the rules.
- Find a participating installer. Choose one that delivers measures under ECO4 on behalf of a supplier such as British Gas, EDF, E.ON, Ovo, Scottish Power or Utility Warehouse.
- Book a home assessment. The installer surveys your home, checks its energy rating and decides which measures qualify.
- Gather your evidence. Have proof of your qualifying benefit and your property details ready for the application.
- Confirm any contribution. Get any payment you are asked for in writing before you agree, and apply before 31 December 2026.
Never pay a third party a fee simply to submit an ECO4 application for you. A genuine installer is paid by the obligated supplier, not by charging you for access to the scheme.
What happens after 2026
Because there is no ECO5, the support model is changing rather than disappearing. After ECO4 closes, funding shifts towards the council-run Warm Homes: Local Grant in England, with the Welsh Government Warm Homes programme playing the equivalent role in Wales, and both can fund glazing for eligible households as part of a fabric upgrade. On top of that, the January 2026 Warm Homes Plan confirmed £1.5bn of extra grant funding aimed at upgrading low-income households in fuel poverty, moving away from the supplier-obligation approach that ECO4 represents.
For most people the practical advice does not change. Only around 15% of households qualify for funding of any kind, so the majority will pay for their own windows and should price the work on that basis rather than wait for a grant. If that is you, it is worth reading whether double glazing is worth it for your home before you spend anything. If you are eligible for ECO4, the message is the opposite: do not delay, because the scheme has a hard closing date and nothing identical is coming after it.
Frequently asked questions
Sometimes, but only if you qualify. ECO4 is means-tested and targets households on income-related benefits, and it can fund up to 100% of a measure, though a contribution is sometimes required. It is not a general scheme that gives everyone free windows, and only around 15% of households qualify for funding of any kind, so confirm your eligibility before you assume the work will be free.
ECO4 was extended by nine months and now runs to 31 December 2026, where the previous end date was 31 March 2026. The government confirmed at the November 2025 Budget that there will be no successor supplier obligation after it, so if you are eligible it is worth applying through an installer before the end of 2026.
No. The government confirmed at the November 2025 Budget that there will be no successor supplier obligation, so there is no ECO5. After ECO4 closes, funding shifts to the council-run Warm Homes: Local Grant and to the extra grant funding announced under the January 2026 Warm Homes Plan.
ECO4 is supplier-funded, not paid for out of general taxation. Larger energy companies are obligated under rules set by Ofgem to deliver energy-saving measures in qualifying homes. Obligated suppliers include British Gas, EDF, E.ON, Ovo, Scottish Power and Utility Warehouse, and you do not have to be their customer to take part.
You cannot apply to ECO4 directly. You apply through a participating installer, who arranges a home assessment and submits the application on your behalf. If your council runs LA Flex, you may also be referred even when you do not meet every standard ECO4 criterion. Never pay a third party a fee just to apply for you.
No. ECO4 covers England, Scotland and Wales only. Northern Ireland had its own Affordable Warmth Scheme, which closed at the end of March 2026, so neither route is open to new applicants there.