How do I check if an installer is accredited?

Check the register itself rather than the logo on the van or the quotation. TrustMark for insulation and most home improvement work, MCS for heat pumps and solar, Gas Safe for anything gas, OFTEC for oil and HETAS for solid fuel. Check the trade or technology, not just that the firm appears at all, because every one of these registers is specific rather than company wide. And look the company up on Companies House, which is free and is the only one that tells you whether the firm taking your deposit is solvent.

Does TrustMark registration mean the work is guaranteed?

Partly. It means a minimum two year workmanship guarantee, twenty five years on insulation, and financial protection for money paid in advance. It does not mean your particular job was inspected, because inspections are a sample on a three year cycle, and it does not survive the business ceasing to trade, which is exactly when people need it. TrustMark's own checks found substandard insulation fitted under government schemes and thirty nine businesses were suspended.

Is MCS certification company wide?

No, and this is the most commonly misunderstood thing about it. MCS certification is granted technology by technology. A firm certified for solar panels is not certified for heat pumps. The directory lists each firm's technologies individually, so check that the scope covers the job you are having done rather than accepting the badge.

What should I check on Companies House before paying a deposit?

Whether the company is in liquidation, administration or receivership. Whether the status says active with a proposal to strike off, which is easy to miss. When it was incorporated. Whether accounts have ever been filed or are overdue. And the directors' other companies, because a new company with the same directors as one that recently went under is the phoenix pattern. It is free, needs no account, and a consumer body found one firm holding close to a million pounds of customers' money when it went into liquidation.

← Home upgrades · Checking a firm

Is the company doing the work actually accredited?

8 registers cover this kind of work and they mean quite different things. Some are the law, some unlock a grant, and some are voluntary. Tell us what work you are having done and we will tell you which ones matter, what a number you have been handed actually belongs to, and what each accreditation does and does not promise. Which is less than the logos suggest.

We have not checked anybody, and we cannot. We do not hold any of these registers and we cannot check a firm for you. Only two of the eight are even searchable from a link: Companies House, which we can send you straight into with the name filled in, and nothing else. The rest are search boxes you have to type into yourself. Anybody offering to tell you on their own site whether a firm is accredited is showing you a copy, and a copy cannot tell you about a suspension that happened this morning.

The thing people assume, that is not true

One line per register. If you read nothing else on this page, read this column.

Scroll sideways to see every column

Register	What it is	The thing people assume that is not true
TrustMark	Quality scheme, endorsed by government	It is not company wide. Registration is per service type, and there are a hundred and fifteen of them. A firm vetted for one trade has not been vetted for the one it is quoting you for.
MCS	Technical certification, per technology	It is explicitly not company wide. A firm certified for solar is not certified for heat pumps. This is the single most useful thing on this page: check the technology, not the badge.
Gas Safe Register	Legal requirement	Being registered does not mean they can legally do your job. Gas Safe says in terms that not all engineers are qualified for all types of gas work. Read the back of the card.
Companies House	Not accreditation at all, but the one that catches the worst	Companies House says on every page that it does not check the accuracy of what is filed. It is a filing cabinet, not a regulator.
RECC	Sales conduct code	It is a sales code, not a technical check. RECC does not inspect your installation.
HIES	Sales conduct code, with financial protection	A code governs how you are sold to, not whether the installer is technically competent.
OFTEC	Competent person scheme, oil	Registration is per work category. Registered to service an oil boiler is not registered to install one, and OFTEC's own search separates the two.
HETAS	Competent person scheme, solid fuel	It is category specific. Solid fuel registration is not authorisation for gas work, and gas can only be done by a Gas Safe registered business.

Which register matters for which job

Insulation, loft, cavity or solid wall No accreditation is required by law to fit insulation. TrustMark registration is required to fit it under a government scheme, and it is the only thing standing between you and the sixty five thousand jobs currently being checked for defects.
Spray foam insulation Nothing is legally required and no grant scheme funds it, which is part of why it is sold the way it is. It can also make a house hard to mortgage. If somebody rang you about it, or rang you about removing it, treat both as a warning.
Heat pump MCS certification for heat pumps specifically is what unlocks the Boiler Upgrade Scheme. Certified for solar is not certified for heat pumps.
Solar panels or battery MCS certification is what unlocks the Smart Export Guarantee, so it matters even without a grant.
Gas boiler This is the only one on the list where working without registration is a criminal offence. Check the business and the individual engineer separately, and read the back of the card.
Oil boiler Not a legal requirement in the way gas is, but an OFTEC registered technician can sign off building regulations, which saves you dealing with building control yourself.
Biomass boiler, stove or wood burner MCS for the Boiler Upgrade Scheme, HETAS for building regulations sign off on solid fuel.
Windows and doors No grant scheme on this site funds windows. If somebody has told you a government scheme will pay for your windows, that is not true of any scheme running in 2026.

Three rules that hold across all of them

Check the trade, not the badge. Every one of these registers is specific. TrustMark covers a hundred and fifteen separate service types and a firm vetted for one has not been vetted for another. MCS is granted technology by technology, so certified for solar is not certified for heat pumps. Gas Safe registration does not mean an engineer may do your particular gas job, which is why the back of the card lists what they can touch. A firm can be genuinely on a register and completely outside its scope for your work.

Check the register, not the paperwork. TrustMark says it is seeing an increasing number of firms advertising themselves as registered when they are not. A card is an object and can be out of date, borrowed or forged. MCS will confirm a certificate exists but only with proof you live at the address, which means a certificate waved at you on a doorstep proves nothing at all.

Absence looks the same as never. Most of these registers show current members only. A firm thrown out last month is simply not there, and looks identical to one that was never on it. So we are registered, plus an empty search result, means not registered now, whatever was true before.

Where this comes from, and where it could be wrong

We hold no registerNot one

Every link here goes to the body that runs the register. A copy held on somebody else's website cannot tell you about a suspension that happened this morning, and this page will never pretend otherwise.

Searchable from a link1 of 8

Only Companies House. We tested the others: they are search boxes built in the browser and they ignore anything put in the address, so we cannot fill them in for you. Saying so is better than a link that lands you on an empty form.

Nothing sold, nothing passed onNo installers

We take nothing from anybody, we recommend no installers, and there is no installer anywhere on this site. This page sends you to the official register and nowhere else.

What the number check can and cannot do

It reads the shape of a number and tells you which register that shape belongs to. That catches somebody quoting a company number as though it were a certification, or a four digit number offered as an MCS certificate. It cannot tell you whether the number is real, whether it belongs to the firm in front of you, or whether it is still valid, and some formats overlap so it will sometimes offer you two answers.

Two of the bodies do not publish a format at all, so a number that matches nothing here is not evidence of anything on its own. It is a reason to ask the firm plainly which register it is for, and then to go and look.

30 price changes logged. Every one had a date you could have known in advance.

Tell us which bills you care about and we will email you when one of them changes, with the figure, the date it starts and a link to the regulator that set it. Free, no account, one click to stop.

Email alerts are not running yet. We would rather say that than take your address and send you nothing. Until they are, the change log carries every dated change the day we find it, and you can bookmark it or follow it in a reader.

Everything, freeAll ten trackers, no account

Ranked on costNever on what a link pays us

SourcedEvery figure links to the body that set it