MCS, TrustMark, NICEIC, Gas Safe: what do they mean?

UK trades have a confusing alphabet soup of accreditations. Here is what each one means and which ones are legally required vs nice to have.

Legally required

Gas Safe Register (formerly CORGI)

• Anyone working on gas appliances (boilers, hobs, cookers) must be on the Gas Safe Register. By law. Non-negotiable.
• Verify at gassaferegister.co.uk. Ask to see the engineer's ID card on site.

Part P / NICEIC / NAPIT / ELECSA

• Electrical work in kitchens, bathrooms, garden buildings or any work in the consumer unit must be carried out by a registered "competent person" (or signed off by Building Control).
• NICEIC and NAPIT are the two main registration schemes. Verify at their respective websites.

Required for specific grants and schemes

MCS (Microgeneration Certification Scheme)

• Heat pumps, solar PV, solar thermal, biomass, batteries.
• Required to apply for the Boiler Upgrade Scheme, Smart Export Guarantee, and most local schemes.
• Verify at mcscertified.com.

TrustMark

• Government-endorsed quality scheme for all home improvements, focused on consumer protection.
• Required for ECO4 and most government-funded retrofit work.
• A TrustMark-registered firm carries a 2-year minimum workmanship warranty backed by an insurer, so if they go bust mid-job you are still covered.

FENSA or CERTASS

• Required for replacement windows and doors to self-certify Building Regs compliance.
• Verify at fensa.org.uk or certass.co.uk.

HETAS

• Required for solid-fuel and wood-burning appliances.

Strongly recommended (but not legally required)

Federation of Master Builders (FMB)

• Vetted membership for general builders. Each member is independently inspected at application.

RICS (Royal Institution of Chartered Surveyors)

• For surveyors. RICS membership is the baseline you want for a building survey or valuation.

RIBA (Royal Institute of British Architects)

• For architects. A RIBA-chartered architect is fully qualified and insured.

How to check

The Verify Credentials tool in Retrofit mode does live lookups against the official MCS, TrustMark and DEA registers. Most other schemes have free public search on their website. Never trust a logo on a van or a website without verifying.