UK Trade Compliance: Part P, Gas Safe, CIS (2026)

Trade compliance in the UK comes down to three questions on every job: is the work notifiable under building regulations, does it need a registered or competent person to carry it out, and does it need certifying afterwards? Get those three right and most of the paperwork looks after itself. This handbook maps the rules that matter across the main trades — electrical work and Part P, gas work and the Gas Safe Register, building regulations, the certificates you must issue, and the Construction Industry Scheme for tax — and points you to the official place to check each one. It’s a map, not legal advice: when a job sits on the line, confirm with the relevant body before you start.

The three questions behind almost every rule

Most compliance headaches in the trades reduce to the same core ideas.

First, is the work notifiable? Some jobs must be signed off against building regulations — either you notify building control yourself, or you’re registered with a competent person scheme that lets you self-certify. Skipping notification is where trades most often come unstuck, because it surfaces years later at sale.

Second, who is allowed to do it? Certain work is legally restricted to registered people — gas work being the clearest example. For other work there’s no registration monopoly, but you’re still expected to be competent and to work to the current standards.

Third, what has to be certified? A lot of trade work generates a certificate the customer needs to keep — proof the job met the standard. No certificate, and even perfectly good work can fail at survey or insurance claim.

Keep those three in mind and the rest of this guide is just the detail for each trade.

Electrical work: Part P, BS 7671 and certification

Electrical safety in dwellings in England and Wales is governed by Part P of the Building Regulations. Part P doesn’t tell you how to wire — that’s BS 7671, the IET Wiring Regulations (the current edition being the 18th, with its amendments). Part P is about which electrical work in a home must meet building regs and be notified.

The practical split is between notifiable and non-notifiable work. Broadly, higher-risk jobs — a new circuit, a consumer unit (fuse board) replacement, and work in special locations such as bathrooms — are notifiable. Smaller like-for-like repairs and additions to existing circuits outside special locations generally are not. Because the exact boundaries can shift with guidance and edition, treat the categories as a prompt to check rather than a fixed list, and confirm the current position for the specific job.

There are two compliant routes for notifiable work. If you’re registered with a competent person scheme — NICEIC, NAPIT, and others operate them — you can self-certify the work and the scheme notifies building control on your behalf. If you’re not registered, you must notify building control directly before starting, and they’ll arrange inspection. The registered route is faster and cheaper per job, which is a large part of why serious domestic sparks join a scheme.

Certification is not optional. Notifiable work needs an Electrical Installation Certificate (EIC); smaller works typically need a Minor Electrical Installation Works Certificate. When you’re testing an existing installation rather than altering it — for a landlord, a sale, or a periodic check — you issue an Electrical Installation Condition Report (EICR), which reports the installation’s condition against BS 7671 and codes any defects. For rented homes, periodic EICRs are a legal requirement for landlords, so this is steady, compliance-driven work.

Don’t describe yourself as “certified” when you mean scheme-registered — the accurate phrasing is “registered with NICEIC/NAPIT” and “competent to BS 7671”.

Gas work: Gas Safe is the law, not a nice-to-have

Anyone carrying out gas work in Great Britain must be on the Gas Safe Register. This is not a voluntary quality badge like some trade directories — it is the legal requirement, and working on gas without it is a criminal matter. Registration is held by the business, and each engineer carries an ID card listing the specific categories of work they’re qualified for (boilers, cookers, meters, commercial, and so on). Working outside your card categories is as much of a problem as not being registered at all.

Homeowners can and increasingly do check an engineer on the Gas Safe Register before letting them touch an appliance, so keep your card current and your details listed correctly. For any gas job, the compliant sequence is: confirm the work falls within your registered categories, carry it out to standard, and leave the customer the appropriate documentation — for example the gas safety record (CP12) that landlords are legally required to obtain annually for rented properties.

Heat pumps, renewables and MCS

As more homes move off gas, the certification centre of gravity shifts towards MCS (the Microgeneration Certification Scheme) for renewable technologies like heat pumps and solar. MCS certification is what lets an installation qualify for government support and gives the homeowner confidence the system was installed to standard.

The clearest example in 2026 is the Boiler Upgrade Scheme, which offers a grant of £7,500 towards an air source or ground source heat pump in England and Wales — and the installer must be MCS-certified for the customer to claim it. If you’re a heating engineer moving into heat pumps, MCS certification isn’t just a quality mark; it’s the gate to a large and growing slice of subsidised work.

Building regulations beyond electrics

Building regulations cover far more than wiring. Structural alterations, certain window and door replacements, drainage, insulation and ventilation, and many extension and conversion works are all controllable. Depending on the job you either go through building control (full plans or a building notice) or, where a competent person scheme covers your trade — such as FENSA or Certass for replacement windows and doors — you self-certify.

For builders, joiners, roofers and glaziers the practical rule is the same as everywhere else in this guide: before you start, ask whether the work is controllable, and if it is, decide your route — self-certify through a scheme you belong to, or notify building control. The customer will want the completion certificate at the end, and its absence is a classic snag at sale.

Water, ventilation and the smaller regimes

Plumbers and heating engineers touch their own set of rules. Work on the water supply is subject to the Water Supply (Water Fittings) Regulations, aimed at preventing contamination and waste, with water suppliers enforcing them. Unvented hot water cylinders require specific competence to install. Ventilation and combustion air requirements sit within building regs and matter enormously wherever there’s a flue or a sealed room. None of these is as headline-grabbing as Part P or Gas Safe, but each can turn a signed-off job into a callback if ignored.

Certification bodies and what they actually do

It helps to know who’s who, because trades often confuse membership, registration and certification.

Gas Safe Register is the official gas registration body — legally required for gas work. NICEIC and NAPIT run competent person schemes for electrical (and other) work, letting members self-certify to building regs. The FMB (Federation of Master Builders) is a trade association — valuable for credibility and support, but membership is not a legal permission to work. MCS certifies renewable installations. FENSA and Certass cover replacement glazing self-certification. CITB is the construction industry training board, relevant to levy and skills rather than day-to-day compliance.

The distinction that trips people up: being a member of a trade body is reputational, while being registered on a legal scheme is permission. A homeowner-facing directory listing is marketing; Gas Safe registration is the law. Keep them straight in your own head and in how you describe yourself to customers.

CIS: the tax side of compliance

Compliance isn’t only safety and standards — the Construction Industry Scheme (CIS) is HMRC’s system for how payments between contractors and subcontractors in construction are taxed, and it catches a lot of trades.

If you pay subcontractors for construction work, you’re likely a contractor under CIS and must verify each subcontractor with HMRC, then deduct the right amount from their labour payments and pay it over. The deduction rates are 20% for a registered subcontractor, 30% for one who isn’t registered, and 0% for a subcontractor with gross payment status. If you’re the subcontractor, registering with CIS is what keeps you on the 20% rate rather than 30% — a direct hit to your cash flow if you skip it.

CIS sits alongside, not instead of, your other tax duties. Making Tax Digital for Income Tax is now phasing in — mandatory from 6 April 2026 for sole traders and landlords with qualifying income over £50,000, from 6 April 2027 over £30,000, and from 6 April 2028 over £20,000 — so growing trades should be moving to digital record-keeping regardless of CIS. And the VAT registration threshold is £90,000 of taxable turnover in a rolling twelve months, at which point registration becomes compulsory.

A pre-job compliance check you can actually use

Before you quote, let alone start, run the three questions on the specific job. Is any part of this work notifiable or controllable under building regs? If yes, what’s my route — self-certify through my scheme, or notify building control? Does the law restrict who can do it (gas, and your own scheme categories for electrical)? What certificates or records must I issue at the end, and has the customer been told they’ll get them? On the money side, does CIS apply to how I’m paying or being paid, and am I registered on the right rate?

Answer those up front and you price the job correctly, avoid the callback, and hand the customer paperwork that stands up years later. That reliability is worth real money — the trades that win repeat work and referrals are the ones whose jobs never come back to bite the homeowner at survey.

FAQ

What is Part P and does it apply to me? Part P is the part of the Building Regulations in England and Wales covering electrical safety in dwellings. It applies to electrical work in homes and determines which jobs are notifiable. It doesn’t replace BS 7671 (the wiring regs) — Part P is about notification and building-regs compliance, BS 7671 is the technical standard you wire to.

Do I legally have to be on the Gas Safe Register to do gas work? Yes. Carrying out gas work in Great Britain without being on the Gas Safe Register is a criminal offence. Registration is held by the business and each engineer’s ID card lists the specific categories they’re qualified for — you must work only within those categories.

What’s the difference between an EIC and an EICR? An Electrical Installation Certificate (EIC) is issued when you carry out new or altered electrical installation work, certifying it meets BS 7671. An Electrical Installation Condition Report (EICR) is issued when you inspect and test an existing installation and report its condition — this is what landlords need periodically for rented homes.

Is being an FMB or trade association member the same as being certified? No. A trade association membership is reputational and supportive but is not legal permission to carry out restricted work. Legal permission comes from the relevant scheme — Gas Safe registration for gas, a competent person scheme like NICEIC or NAPIT for self-certifying electrical work.

Do I need to worry about CIS if I only occasionally use a subcontractor? Quite possibly, yes. If you pay subcontractors for construction work you’re likely a contractor under CIS and must verify them and deduct at the correct rate (20% registered, 30% unregistered, 0% gross status). Check your position with HMRC rather than assuming occasional use is exempt.

Where should I check the current rules before a job? Go to the source: gov.uk for building regulations and CIS, the Gas Safe Register for gas, your competent person scheme (NICEIC, NAPIT and others) for electrical notification, and MCS for renewables. Where a job sits on the boundary of notifiable, confirm before you start.

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Related reading: building regulations for trades · do I need Part P · how to check a Gas Safe engineer · the Building Safety Act for tradespeople