What the ECO4 contractor list is and who maintains it
The ECO4 contractor list is the official register of installers authorised to deliver funded energy-efficiency measures under the Energy Company Obligation (ECO4) scheme, which runs until March 2026. It is not a single government-run database. Instead, each obligated energy supplier, such as British Gas, E.ON, Octopus Energy, and Scottish Power, publishes its own list of approved contractors, typically on its ECO4 programme page (Ofgem, 2026). To appear on a supplier’s list, contractors must hold relevant certifications, including MCS certification for heat pumps and solar panels, and TrustMark registration for all installation work.
Each energy supplier (British Gas, E.ON, Octopus Energy) runs its own ECO4 contractor list. Check your supplier’s programme page for approved installers who can deliver funded measures at zero cost. Compare lists to ensure eligibility.
- Each supplier (British Gas, E.ON, Octopus) publishes its own ECO4 contractor list.
- Contractors must hold MCS certification and TrustMark registration to qualify.
- ECO4-approved contractors can install measures at zero cost to eligible homeowners.
- Without an ECO4 contractor, a gas boiler installation costs £5,000–£8,000.
- Loft and cavity wall insulation cost £0 with an ECO4-approved installer.
- What the ECO4 contractor list is and who maintains it
- The key difference between an ECO4-approved contractor and a general installer
- Quick numbers typical costs with and without an ECO4-approved contractor
- How to find the official ECO4 contractor list for your area
- Eligibility, certification, and how to verify an ECO4 contractor
- The direct answer where to get the official ECO4 contractor list
- What to do if your preferred installer is not on the ECO4 list
The key difference between an ECO4-approved contractor and a general installer
An ECO4-approved contractor has passed the supplier’s due diligence checks, including proof of certification, public liability insurance, and compliance with Microgeneration Certification Scheme (MCS) standards for renewable technologies. A general installer, even if certified for boilers under Gas Safe Register, may not appear on any ECO4 list and therefore cannot deliver measures that qualify for ECO4 funding (Ofgem, 2026). The financial difference is substantial. An ECO4-approved contractor can install a first-time central heating system at zero cost to the homeowner, whereas a general installer would charge the full market rate, typically £5,000–£8,000 for a gas boiler installation (Energy Saving Trust, 2026).
Quick numbers typical costs with and without an ECO4-approved contractor
The table below compares typical installation costs and annual savings for common ECO4 measures, based on published data from the Energy Saving Trust, MCS, and DESNZ.
| Measure type | Typical cost without ECO4 (GBP) | Typical cost with ECO4 (GBP) | Average annual saving on energy bills (GBP) |
|---|---|---|---|
| Loft insulation (270mm) | £500–£1,000 | £0 | £200–£300 |
| Cavity wall insulation | £400–£800 | £0 | £200–£300 |
| Air source heat pump | £7,000–£13,000 | £0 | £300–£500 |
| Gas boiler replacement | £2,500–£4,000 | £0 (if eligible) | £100–£200 |
Sources: Energy Saving Trust, 2026; MCS, 2026; DESNZ, 2026.
How to find the official ECO4 contractor list for your area
Start by checking the ECO4 programme page of the energy supplier you pay your bills to. If you are unsure which supplier that is, use the Ofgem supplier lookup tool (Ofgem, 2026). Each supplier’s ECO4 page typically includes a “Find an installer” tool or a downloadable PDF of approved contractors, filtered by postcode or region (GOV.UK, 2026). If you are on benefits or have a low income, you can also contact your local council’s energy advice team. Many councils maintain a list of ECO4 contractors they work with, which can be a useful alternative if your supplier’s list is limited.
Eligibility, certification, and how to verify an ECO4 contractor
To be on an ECO4 contractor list, an installer must hold MCS certification for renewable technologies such as heat pumps and solar PV, and TrustMark registration for all measures. For gas boilers, they must also be Gas Safe registered (Gas Safe Register, 2026). To verify a contractor, check their MCS certificate number on the MCS Installer Database (MCS, 2026) and their TrustMark registration on the TrustMark website (TrustMark, 2026). You can also ask the contractor for their ECO4 supplier approval letter, which confirms they are on the supplier’s list and authorised to claim the funding on your behalf.
The direct answer where to get the official ECO4 contractor list
The official ECO4 contractor list is not a single website. It is a collection of lists published by each obligated energy supplier on their ECO4 programme page. To get the list, go to the ECO4 section of your energy supplier’s website, for example, British Gas’s ECO4 page or E.ON’s ECO4 page, and look for the “Approved installers” or “Find an installer” tool (Ofgem, 2026). If you do not know your supplier, use the Ofgem “Find my supplier” tool and then follow the link to their ECO4 page (GOV.UK, 2026). how to check if you qualify for ECO4 funding
What to do if your preferred installer is not on the ECO4 list
If an installer is not on any ECO4 supplier list, they cannot deliver measures under the scheme, meaning you would have to pay the full cost yourself, typically £5,000–£13,000 for a heat pump. You can ask the installer to apply to join a supplier’s ECO4 list, but this process can take weeks and is not guaranteed. The installer must hold valid MCS and TrustMark certifications first (MCS, 2026). Alternatively, search for a different installer using the MCS Installer Database or TrustMark’s “Find a tradesperson” tool, then check whether that installer appears on your supplier’s ECO4 list (TrustMark, 2026). what to do if your ECO4 application is rejected
Frequently Asked Questions
There is no single government-run list. Each obligated energy supplier publishes its own ECO4 contractor list on its programme page, as confirmed by Ofgem in 2026. Check British Gas, E.ON, Octopus Energy or Scottish Power for their approved installers.
Visit your energy supplier’s ECO4 programme page to view its contractor list. You can also contact TrustMark or MCS for verified installers, as all ECO4 contractors must hold both certifications according to Ofgem.
An ECO4 contractor has passed supplier due diligence checks and holds MCS certification for renewables. A general installer may not appear on any ECO4 list and cannot deliver funded measures, meaning you pay full price, £5,000–£8,000 for a gas boiler (Energy Saving Trust, 2026).
No. Only contractors on a supplier’s ECO4 list can install funded measures. They must hold MCS certification for heat pumps and solar panels, and TrustMark registration for all work, as set by Ofgem.
Typical savings are £200–£300 per year for loft or cavity wall insulation installed at zero cost. An air source heat pump via an ECO4 contractor saves £200–£700 annually compared to a gas boiler, based on Energy Saving Trust data.
