Warm Homes work runs on two separate certification regimes, and which one applies depends on the measure you install, not the scheme you are bidding into. Here is how the split works.
Jamie Duncan
The question we get asked most often by installers looking at work funded through Warm Homes is some version of "what do I need to be certified in?" It sounds like it should have a one-line answer. It does not, and the reason is worth understanding before you spend money on the wrong route.
There is no such thing as Warm Homes certification. What exists is two separate quality regimes that government schemes sit on top of, and the one that applies to you is decided by the measure you install rather than the fund you are bidding into. An installer doing external wall insulation and an installer doing air source heat pumps can be delivering work under the same grant and be certified against completely different standards.
Get the split right and the pathway is clear. Get it wrong and you spend six months and several thousand pounds achieving a certification that does not let you do the work you wanted.
The Warm Homes Plan sets out both regimes in the same section. For energy efficiency measures under DESNZ schemes, installers must be certified to PAS 2030, installations must be compliant with PAS 2035, and installers must also be TrustMark registered (or equivalent) and join a relevant certification body.
For microgeneration installations under DESNZ schemes, installers must hold MCS certification (or equivalent for solar panel and battery installations), and those installations must meet the relevant MCS installation standard. The plan also has MCS installers joining a consumer code, and flags that this will change as a consequence of the MCS reforms. It since has. In June 2026 DESNZ recognised the redeveloped MCS Scheme as a Code of Practice for the Boiler Upgrade Scheme, and consumer code membership stopped being mandatory for installers certified to it.
That is the whole decision tree. Insulation, ventilation, glazing and other fabric work sits on the PAS side. Heat pumps, solar PV and batteries sit on the MCS side.
Which route applies to you
The Warm Homes Plan is unusually blunt about this. Set against each other, retrofit inside a government scheme and retrofit outside one look like this: compliance with Building Regulations is a legal requirement in both cases, but MCS certification or TrustMark accreditation is required only inside a government scheme, and not required (though recommended) outside it. The same is true of working to MCS standards or PAS 2030 and 2035.
So if your business is entirely able-to-pay work, funded by the customer, you are not legally obliged to hold any of this. What you lose is access to the grant-funded market, and in practice most of the residential heat pump market, because the Boiler Upgrade Scheme requires MCS. We have written separately about what changes when you move from grant-funded work to selling to homeowners directly, and the commercial case usually decides this rather than the compliance one.
If you install low-carbon heat or generation, MCS is the route and it is getting more firmly so. Government confirmed in October 2025, in its response to the consultation on certification requirements for clean heat schemes, that MCS is the sole certification scheme for clean heat measures under the Boiler Upgrade Scheme, the Warm Homes Social Housing Fund and the Warm Homes Local Grant. Those measures previously had to be certified by MCS or equivalent, and the option for multiple certification schemes has gone.
Two things are worth planning around. The first is the redeveloped MCS installer scheme, which is moving every certified installer across on a timetable set by your certification body rather than by you. Most move during 2026, and 31 March 2027 is the deadline by which every MCS certified installer has to be operating under it. The second is that government is working with MCS on a skills test intended to make it easier to register as a certified installer and deliver heat pumps under government schemes, alongside reforms aimed at reducing cost and bureaucracy.
If you are not certified yet, our guide to MCS certification for solar and heat pump installers covers what the assessment involves, what it costs and the umbrella scheme route. If you are weighing whether the market supports the investment, the heat pump installer economics piece has the margin arithmetic.
The PAS side has more moving parts, and they have to be assembled in a particular order.
PAS 2030 is the specification your business is certified against, and TrustMark is clear that the certifying body must be accredited by UKAS. It sets requirements for competence, technical ability and quality, which in practice means standing up a quality management system rather than just demonstrating that your fitters know their trade.
PAS 2035 is the standard the installation has to comply with, and it takes a whole-house approach: the property, the environment, the occupancy and the householder's objectives all feed into which measures are appropriate. The two are inextricably linked, which is why you cannot treat PAS 2030 as a certificate you collect and then carry on working the way you did before.
The role most installers underestimate is the Retrofit Coordinator. Under PAS 2035 guidance all domestic retrofit projects should use one, and TrustMark's position is that anybody wanting to become a Retrofit Coordinator must hold the Level 5 Diploma before joining an approved Scheme Provider. That is a qualification with a lead time, not a form.
One body per measure type
Since May 2025, installers can only be certified with one body for each energy efficiency measure type, which has always been the case for microgeneration. The change closed a route where a business could register with several certification bodies and avoid audits on the quality of its work. If you are currently spread across bodies, consolidating is not optional.
Plenty of our customers do. A business installing a heat pump alongside insulation under the same grant is delivering two measures under two regimes, with two sets of evidence, two audit trails and two sets of renewal dates.
The operational problem this creates is not the certification itself, it is proving compliance afterwards. Audits arrive months after the job, and the evidence has to be findable: certificate numbers, commissioning records, photographs, sign offs, and the paperwork that shows the installation met the standard on the day.
This is where a lot of otherwise well-run businesses come unstuck, and it is the same failure mode we see in solar commissioning compliance and heat pump commissioning compliance. The work was done correctly. Nobody can prove it quickly.
In Payaca, this is what custom fields are for. Installers running dual certification typically build one compliance fieldset per regime, so an MCS certificate number, a DNO reference or an EPC rating each has a structured home on the project rather than living in a note. Site photos and commissioning paperwork go on the project file store as the job runs, and certificates can be shared straight to the customer rather than emailed and lost. When the audit lands, the project is the answer.
Two changes are worth watching if you are planning certification spend over the next year.
Government has said it will consult on options to reduce the number of certification bodies operating in the energy efficiency and microgeneration space, on the basis that competition between them confuses consumers about where to go for redress. It has also said it will consult on bringing oversight of installations for government schemes under closer government control, and on the role of the Warm Homes Agency.
Neither changes what you need today. Both point in the same direction: fewer bodies, more centralised oversight, and a system where your certification is more visible to government than it has been. Battery installers should also note that PAS 63100, covering protection against fire of battery energy storage systems in dwellings, was released in 2024 and sits alongside the MCS route rather than replacing any part of it.
If you install heat pumps, solar or batteries, start with MCS and read the redeveloped scheme guide so the transition does not catch you mid-quarter. If you install fabric measures, start with a UKAS-accredited certification body for PAS 2030 and work out your Retrofit Coordinator arrangement early, because the Level 5 Diploma is the long pole.
If you are doing both, the certifications are the easy half. The half that decides whether you keep the work is whether you can produce the evidence on demand, across two regimes, months later. That is a systems question, and it is worth solving before volume makes it urgent rather than after.
For the wider picture on what the plan funds and how the pipeline is likely to move, see what installers need to know about the Warm Homes Plan and our analysis of the delivery constraint that shapes the next four years. If you are choosing the system that will hold all this together, we compared the options in the best CRM software for solar installers, and the heat pump installer and solar installer pages set out how Payaca handles compliance work specifically.
Certification decides whether you can bid. Evidence decides whether you keep the work. Book a demo and we will show you how installers running both regimes keep their compliance trail on the project.
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