Employee or Subcontractor? Classifying Construction Workers Correctly

Key Takeaways

• Employment status is decided by the reality of the working relationship, not by the wording of a contract or by how someone invoices you.

• The three core tests are control, personal service (substitution), and mutuality of obligation — no single factor decides it on its own.

• CIS registration does not make someone self-employed. Contractors must assess each subcontractor's employment status separately, and paying someone through CIS is not evidence of self-employment.

• Getting it wrong can mean back PAYE, employer National Insurance, interest and penalties from HMRC, plus tribunal claims for holiday pay and the National Minimum Wage.

• The Fair Work Agency, live since 7 April 2026, can carry out unannounced inspections and impose penalties of up to 200% of amounts owed, going back six years.

Whether someone on your site is an employee or a genuine subcontractor depends on how the working relationship actually operates — not on what the paperwork calls it. HMRC and employment tribunals look at who controls the work, whether the individual must do it personally, and whether both sides are obliged to offer and accept work. Construction has the highest rate of self-employment in the UK economy, which is exactly why HMRC scrutinises the sector closely.

Why this matters more in construction than anywhere else

Construction runs on flexible labour, and self-employment is genuinely normal in the trade. That's not the problem. The problem is that the same flexibility makes it easy to treat someone as self-employed when, in substance, they're working as an employee — turning up when told, using your tools, taking instruction, and doing the same job week after week for one payer.

HMRC knows this, and construction is one of its priority sectors for employment status enquiries. The cost of getting it wrong falls on the contractor, not the worker.

The three employment statuses

For employment rights, UK law recognises three categories. For tax, there are only two — you're either employed or self-employed. That mismatch is a common source of confusion.

Status	Employment rights	Tax treatment
Employee	Full rights: holiday pay, sick pay, unfair dismissal protection, redundancy	PAYE — tax and NI deducted at source
Worker	Core rights: holiday pay, National Minimum Wage, rest breaks	Usually treated as employed for tax
Self-employed	No employment rights; runs their own business	Self Assessment; CIS may apply

Someone can therefore be self-employed for tax but still count as a "worker" with holiday pay and minimum wage rights — a distinction that has cost businesses dearly in tribunal cases.

The three key tests

1. Control

Who decides what work is done, how it's done, when, and where? The more you direct the detail, the more it looks like employment. A genuine subcontractor is engaged to deliver a result and decides how to achieve it. An employee is told how to do the job and works the hours you set.

In practice: telling a bricklayer which wall to build is fine. Setting their start time, supervising their method, and requiring them to report daily points towards employment.

2. Personal service and substitution

Must the individual do the work personally, or can they send someone else? A genuine right to substitute — one that's real and actually usable, not just a clause in a contract — is one of the strongest indicators of self-employment.

In practice: if a subcontractor could send an equally qualified tradesperson and you'd accept them, that supports self-employment. If you'd refuse, you're buying that person specifically, which points to employment. Tribunals look at whether substitution has ever actually happened.

3. Mutuality of obligation

Are you obliged to offer work, and are they obliged to accept it? Continuing obligation on both sides suggests employment. A genuine subcontractor can turn work down and you have no duty to provide it.

In practice: a subbie who's been on your books full-time for two years, always given work and always taking it, starts to look like an employee regardless of how they're paid.

Other factors that count

No single test decides status. Tribunals and HMRC weigh the whole picture, including:

• Financial risk — do they bear the cost of putting defective work right, or quote fixed prices that could lose money?

• Equipment — do they provide their own tools and materials?

• Integration — are they part of your team, on your org chart, wearing your branding?

• In business on their own account — do they have other clients, their own insurance, marketing, and a real business behind them?

The biggest misconception: CIS does not decide status

This is the single most costly misunderstanding in the sector. Registering someone under CIS and deducting 20% does not make them self-employed. CIS is a tax collection mechanism, not a status determination.

In fact, the obligation runs the other way: as a CIS contractor, you are responsible for assessing each subcontractor's employment status before you pay them. If HMRC later decides someone you paid through CIS was really an employee, you'll owe the PAYE and employer National Insurance that should have been operated — with interest and penalties on top, and the CIS deductions only partly offsetting the bill.

Because status is fact-specific and the liability sits with you, this is an area where a construction-specialist accountant is worth involving before a long-term arrangement beds in rather than after HMRC asks.

How to check someone's status

HMRC provides a free online tool, CEST (Check Employment Status for Tax), on GOV.UK. It asks about substitution, control, financial risk, and the nature of the engagement, then gives a determination. HMRC will stand by the result provided your answers accurately reflect the real arrangement and the arrangement doesn't change.

Two honest caveats. CEST has been criticised for how it handles mutuality of obligation, and its output isn't binding on an employment tribunal — it covers tax status, not employment rights. And rushing the questions to get the answer you want is worse than useless, because the determination only protects you if the inputs were true.

Whatever you conclude, save a dated copy of the assessment. Written evidence that you considered status properly is valuable if HMRC comes asking.

What's changing: the Employment Rights Act 2025

The Employment Rights Act 2025 received Royal Assent on 18 December 2025 and is being phased in through 2026 and 2027. Two developments matter most for construction businesses:

• The Fair Work Agency (FWA) launched on 7 April 2026, merging HMRC's National Minimum Wage team, the Gangmasters and Labour Abuse Authority, and the Employment Agency Standards Inspectorate into a single enforcement body. It can make unannounced inspections, demand documents, interview staff, and impose penalties of up to 200% of amounts owed, reaching back six years.

• A "single worker status" — collapsing employee and worker into one category — remains a government commitment rather than law. The promised consultation has not yet been published, so the existing three-tier framework still applies. It's worth watching, because it would significantly change how flexible construction labour is classified.

The practical takeaway: enforcement has got sharper, and the window for informal arrangements is narrowing.

What happens if you get it wrong

Misclassification exposes a contractor on two separate fronts:

From HMRC: unpaid PAYE and employer National Insurance for the whole period, plus interest and penalties. The liability is the contractor's, not the worker's.

From employment tribunals: claims for unpaid holiday pay, National Minimum Wage shortfalls, and unlawful deductions — and, if the individual is found to be an employee, potentially unfair dismissal. The Employment Rights Act has also extended time limits for bringing most tribunal claims, so historic arrangements stay exposed for longer.

Landmark cases such as Pimlico Plumbers and Uber established the principle clearly: the written contract is a starting point, not a shield. What matters is what actually happens on site.

Practical steps for contractors

1. Assess status before the first payment, not after a dispute.

2. Run CEST honestly and keep a dated PDF of the outcome for each engagement.

3. Make the contract match reality — and if the reality is employment, fix the reality rather than the wording.

4. Give genuine substitution rights where the arrangement truly allows them, and accept a substitute if one is offered.

5. Review long-running engagements every 6–12 months. Status can drift: someone who started as a genuine subbie can become an employee in substance over time.

6. Keep the evidence — contracts, insurance certificates, invoices, and status assessments.

Frequently Asked Questions

Does being CIS registered make someone self-employed? No. CIS is a tax deduction scheme, not a test of employment status. Someone can be registered under CIS and still be legally an employee if the working relationship has the hallmarks of employment. As the contractor, you're responsible for assessing each subcontractor's status separately, and paying through CIS won't protect you if HMRC disagrees.

What are the main tests for employment status? Control (who decides what, how, when and where the work is done), personal service (whether the individual must do the work themselves or can send a substitute), and mutuality of obligation (whether you must offer work and they must accept it). Other factors include financial risk, who provides equipment, integration into your team, and whether they're genuinely in business on their own account.

Can a subcontractor become an employee over time? Yes, in substance. Someone engaged as a genuine subcontractor can drift into employment status if the relationship changes — working set hours, taking direction, using your equipment, and working exclusively for you over a long period. This is why long-running engagements should be reviewed every 6 to 12 months rather than left unexamined.

What happens if HMRC decides I've misclassified a worker? You can be liable for the PAYE and employer National Insurance that should have been deducted, plus interest and penalties, and the liability falls on you as the contractor rather than the worker. You may also face employment tribunal claims for holiday pay, National Minimum Wage, or unfair dismissal. Because the sums build up over years, it's worth having a construction-specialist accountant review your arrangements before a problem arises.

Is HMRC's CEST tool reliable? It's a useful starting point and HMRC will stand by the result if your answers accurately reflect the real working arrangement. But it only determines status for tax, isn't binding on an employment tribunal, and has been criticised for how it treats mutuality of obligation. Answer it honestly, keep a dated copy, and take advice on borderline cases.

Not sure where your workers stand?

Employment status is one of the most expensive things to get wrong in construction — and with the Fair Work Agency now able to look back six years, it's harder to leave unchecked. Talk to the SiteLedger team on 0161 513 0027 and we'll review how your subcontractors are engaged and where your risk sits. As construction-specialist accountants, this is the sector we work in every day.

Written by the SiteLedger team — construction-specialist accountants. Last reviewed: July 2026. Rules and figures apply to the 2026/27 UK tax year. Employment status is highly fact-specific and has employment-law as well as tax consequences; this is general guidance, not personal tax or legal advice. Speak to us about your arrangements, and take legal advice on contentious cases.