TrustMark accreditation for installers

The single most important thing to know about TrustMark accreditation in 2026

If you are planning a home energy upgrade with government funding, the installer you hire must be TrustMark registered. This is not optional. TrustMark is the government-endorsed quality scheme for tradespeople in the UK, and since the Great British Insulation Scheme and the expanded Boiler Upgrade Scheme launched, TrustMark accreditation has become a mandatory requirement for any installer working on government-funded home energy improvements.

The direct answer is this: without TrustMark accreditation, you cannot access the Boiler Upgrade Scheme grant (currently £7,500 for an air-source heat pump) or the Great British Insulation Scheme funding (GOV.UK, 2026). TrustMark accreditation is not a qualification in itself. It is a consumer protection framework that verifies the installer holds the correct technical certifications like MCS, Gas Safe, or FENSA, and is committed to codes of conduct, dispute resolution, and financial protection.

What TrustMark accreditation means for your installer’s qualifications

TrustMark does not replace technical certifications. It sits on top of them as an umbrella scheme that verifies the installer meets consumer protection standards. For example, an installer must hold MCS certification for heat pumps and solar PV, or Gas Safe registration for gas boilers, before they can become TrustMark registered.

To be TrustMark registered, an installer must also have public liability insurance, a clear complaints process, and must adhere to a code of conduct that includes providing written quotes and avoiding high-pressure sales tactics (TrustMark, 2026). For homeowners, this means TrustMark accreditation is a shortcut to verifying that an installer is properly qualified and insured, without you having to check multiple registers yourself (MCS, 2026).

Quick numbers, TrustMark coverage and grant amounts you can access

The Boiler Upgrade Scheme heat pump grant is £7,500 for both air-source and ground-source installations (DESNZ, 2026). The Great British Insulation Scheme offers up to £1,500 per measure (Ofgem, 2026). TrustMark registration is free for homeowners to search, but installers pay a fee (TrustMark, 2026).

How to verify an installer’s TrustMark accreditation (the direct answer to “trustmark accreditation”)

The simplest method is to use the official TrustMark website’s “Find a TrustMark Registered Business” search tool. This lets you search by postcode, trade, or business name (TrustMark, 2026). On the search results page, you will see the installer’s TrustMark registration number, the date they were registered, and a list of the technical certifications they hold (e.g., MCS, Gas Safe, FENSA). This is the only place you can confirm all in one step.

You can also cross-check the installer’s technical certification on the relevant register: MCS installers at mcs-certified.com, Gas Safe engineers at gassaferegister.org.uk, and FENSA at fensa.org.uk. But TrustMark already verifies these for you. Beware of installers who claim to be “TrustMark approved” but do not appear on the official register. Always check directly, never rely on a logo on a van or website (GOV.UK, 2026).

The cost of not using a TrustMark-accredited installer for government-funded work

If you hire an installer who is not TrustMark registered, you will be ineligible for any government grant funding for that installation. The grant is paid directly to the installer, and the scheme administrator (Ofgem for the Boiler Upgrade Scheme, or your energy supplier for the Great British Insulation Scheme) will only release funds to a TrustMark-registered business (Ofgem, 2026).

You also lose access to the TrustMark dispute resolution service, which is a free, independent process for resolving complaints if the work is faulty or incomplete. Without it, you would have to pursue the installer through small claims court or other legal routes (TrustMark, 2026). Some installers may offer a “discount” equivalent to the grant amount without going through the scheme. This is almost always a red flag, as it bypasses the consumer protections built into the grant process, including the requirement for the installer to provide a guarantee.

Eligibility rules, what TrustMark does and does not cover for homeowners

TrustMark accreditation is required for installers, not for homeowners. You do not need to be TrustMark registered yourself to receive a grant, but the installer you hire must be. TrustMark covers all trades related to home energy improvements: heating (including heat pumps and boilers), insulation (cavity wall, loft, solid wall, floor), solar PV and solar thermal, windows and doors, and even roofing and electrical work if related to energy efficiency (TrustMark, 2026).

However, TrustMark does not cover building work that is purely cosmetic or structural without an energy-efficiency component. For example, a general builder for a kitchen extension would not need TrustMark accreditation unless the work includes insulation or heating upgrades. For the Boiler Upgrade Scheme specifically, the installer must also be MCS certified for heat pumps, and TrustMark accreditation is a separate additional requirement (DESNZ, 2026).

How to check if an installer is TrustMark accredited, step by step

Step 1: Go to the TrustMark website and click “Find a TrustMark Registered Business”. Do not use a search engine link to an installer’s own site. Step 2: Enter the installer’s business name or postcode. The search will return only businesses that are currently registered and in good standing. Step 3: Click on the business name to see their registration number, registration date, and a list of the technical certifications they hold (e.g., MCS, Gas Safe, FENSA). This confirms they are qualified for the specific work you need. Step 4: Check the “Schemes” tab to see which government schemes the installer is registered to work under (e.g., Boiler Upgrade Scheme, Great British Insulation Scheme). Not all TrustMark installers are signed up for every scheme. Step 5: If you are using a specific grant, also verify on the grant scheme’s own website (e.g., Ofgem’s Boiler Upgrade Scheme installer list) that the installer is listed there. TrustMark alone is necessary but not sufficient for some schemes (Ofgem, 2026).

TrustMark accreditation and the future of home energy grants in 2026

In 2026, the government has consolidated several energy-efficiency schemes under a single framework that requires TrustMark accreditation for all installers. This includes the Boiler Upgrade Scheme, Great British Insulation Scheme, and the Social Housing Decarbonisation Fund (for homeowners in social housing) (DESNZ, 2026). The government has also announced that from 2027, all new gas boiler installations will be banned in new-build homes, and the Boiler Upgrade Scheme grant for heat pumps will increase to £7,500 (already in place for 2026).

TrustMark will remain the gatekeeper for all grant-funded installations. There is no sign that TrustMark requirements will be relaxed. In fact, the government is expanding the scheme to cover more trades, including electric vehicle charge point installers, as part of the Net Zero strategy (TrustMark, 2026). How to choose a heat pump installer Great British Insulation Scheme explained