Why employment status matters under CIS
The Construction Industry Scheme is a deduction and reporting mechanism, not an employment status ruling. A subcontractor can be registered under CIS, paid with a monthly statement and a 20% deduction, and still be, in legal and tax terms, an employee of the contractor who hired them. HMRC treats these as entirely separate questions.
Get it wrong and the contractor becomes liable for:
- Backdated PAYE on all payments made to the misclassified worker, grossed up as if the CIS payments were net pay.
- Employer NIC at 15% on earnings above £5,000 a year (the 2026/27 rate, carried from April 2025), for every year the misclassification ran.
- Late-payment interest and penalties on both liabilities.
- Gross Payment Status consequences from 6 April 2026, if the arrangement implicates supply-chain due diligence under Finance Act 2026.
For a contractor who has run the same arrangement for two or three years with multiple workers, the reclassification bill arrives as a single demand covering several years of accumulated liability.
The three HMRC tests for employment status
Employment status is determined by weighing a set of factors. Three tests carry the most weight in construction cases and in case law. All three are assessed together.
1. Control: who decides how the work is done?
The control test asks whether the engager directs not just what is done but how, when and where it is done. A genuine subcontractor delivers an outcome and decides their own methods, sequence and hours. HMRC looks past surface-level site instructions to whether the engager controls the manner of working. A plasterer supervised daily by a site manager, told where to work and at what hours, looks more like an employee. A groundwork contractor who sets their own sequencing and answers only for the finished drainage run looks more like a subcontractor.
2. Personal service: can the worker send someone else?
The personal service test asks whether the worker must do the work themselves. A genuine business can, in principle, send a substitute. The right must be practical and exercisable, not a clause buried in a contract neither party considers. HMRC looks at how the arrangement works in practice. A site operative who has never sent a substitute and whose contractor would refuse one fails this test regardless of what the contract says.
3. Mutuality of obligation: is there a continuing duty to work?
The mutuality of obligation test asks whether the contractor is obliged to offer work and the worker is obliged to accept it. A genuine self-employed arrangement is project-by-project: the subcontractor tenders, wins or loses, and has no expectation of future work. Long-running CIS arrangements often fail here. A labourer working exclusively for one contractor for 18 months on a regular fortnightly payment looks very much like someone in an ongoing employed relationship.
Employment status test summary
| Test | Self-employed indicator | Employed indicator |
|---|---|---|
| Control | Worker decides own methods, sequence and hours; answers for the end result only | Engager directs how, when and where the work is done; daily supervision by site manager |
| Personal service | Genuine, practical right to send a substitute; substitute has been used or could be without objection | Worker must attend in person; engager assigns by name; substitution would be refused |
| Mutuality of obligation | Project-by-project engagement; no expectation of further work; worker tenders independently | Ongoing engagement; contractor obliged to provide work; worker expected to attend and accept it |
| Equipment and tools | Worker supplies and owns own tools and specialist equipment | Engager provides all equipment; worker brings only themselves |
| Financial risk | Worker bears cost overruns, rectification, own insurance; quotes fixed prices | Worker paid regardless of outcome; no financial stake in the result |
| Integration | Treated as a separate business; separate invoices for specific jobs; multiple clients | Treated as part of the workforce; on rotas, team lists or staff communications |
No single indicator is decisive. HMRC and employment tribunals weigh all of them, with control, personal service and mutuality of obligation carrying the most weight in construction disputes. The stronger and more consistent the self-employed indicators across the table, the lower the reclassification risk.
The CEST tool: useful, but not the whole answer
HMRC's Check Employment Status for Tax (CEST) tool asks a structured set of questions and returns a result of employed, self-employed, or indeterminate. HMRC will stand behind the result where the answers reflect the true arrangement, so it is worth running and keeping as a record of due diligence. Three limitations matter in practice.
- It does not fully test mutuality of obligation. An arrangement that passes CEST can still fail a tribunal test on mutuality grounds.
- It is not binding. A self-employed CEST result is evidence of process, not a defence if HMRC later disagrees.
- It can return "indeterminate". For borderline arrangements it often cannot reach a conclusion, leaving the contractor carrying the risk.
Use CEST to flag clear-cut cases. For anything long-term or exclusive, a proper analysis of real working arrangements is more reliable than a questionnaire result.
The false self-employment risk: what misclassification costs a contractor
When HMRC reclassifies a CIS worker as an employee, it treats the CIS payments as net pay, grosses them up to derive the implied gross salary, and calculates the PAYE and employer NIC that should have been operated. For 2026/27, employer NIC runs at 15% on earnings above £5,000 a year, introduced in April 2025.
Worked example: joiner paid via CIS for two years
A contractor engages a joiner via CIS on the registered 20% rate, and the joiner takes home £40,000 a year after the CIS deduction. HMRC reclassifies the arrangement as employment for both years and treats that £40,000 as net pay.
- Implied gross salary: £40,000 net grossed up at basic rate = roughly £50,000 a year.
- Employer NIC: 15% on (£50,000 minus £5,000 threshold) = 15% x £45,000 = £6,750 a year.
- Two-year employer NIC liability: approximately £13,500, before interest and penalties.
- PAYE income tax: additional liability on top, partly offset where the worker paid some tax through CIS deductions, but the employer's PAYE exposure is not fully eliminated.
The total bill can easily exceed £20,000 for a single two-year arrangement. Scale that across several workers and the exposure becomes material very quickly.
False self-employment and the GPS connection
From 6 April 2026, Finance Act 2026 added a further consequence for contractors who hold Gross Payment Status. HMRC can revoke GPS immediately, with no advance notice, under the "knew or should have known" standard, where a contractor has operated an irregular supply chain. A contractor who routinely engages workers under CIS without checking employment status properly risks falling on the wrong side of that standard.
Losing GPS means incoming payments are subject to a 20% deduction instead of 0%. On £500,000 a year that is roughly £100,000 a year withheld from working capital. GPS removed on those grounds triggers a 5-year reapplication ban. Under sections 62A and 62B of Finance Act 2004 (inserted by Finance Act 2026), a person who makes a payment knowing that a connected party has deliberately failed to comply with CIS faces a penalty of 20% of the payment (s.62A), while a person who makes a return with that knowledge faces a charge equal to the whole sum the return treats as paid, 100% of it (s.62B). The liability attaches to the payer or return-maker. Where a company is involved, HMRC can also pursue its officers personally under the existing officer-liability rules. See our guide to CIS supply chain compliance and due diligence for how to run the checks that protect GPS.
What a genuine CIS subcontractor looks like
The safest position is an arrangement that clearly passes all three tests. A genuinely self-employed CIS subcontractor typically presents a consistent picture across the following:
- Works for more than one contractor, either simultaneously or in short succession, rather than exclusively for one engager month after month.
- Supplies and owns their own tools and specialist equipment, rather than drawing from a site store or using equipment the contractor provides.
- Invoices for specific jobs at an agreed price rather than being paid a regular hourly or daily rate with no variation for output.
- Has no set hours imposed by the contractor; starts and finishes at their own discretion within the job requirement.
- Bears financial risk: they are responsible for rectifying defects at their own cost and their fee does not increase if the job takes longer than estimated.
- Has a documented, genuine and exercised right to substitute: another appropriately skilled person can and does step in.
Quick self-assessment checklist for workers
Workers unsure of their own position can start with these questions.
- Do you work for more than one contractor, or only for one?
- Do you use your own tools for most jobs?
- Do you invoice for specific jobs rather than receiving a regular wage?
- Could you send someone else to do the work if you were unavailable?
- If the job takes longer, do you bear the cost, or does the contractor simply pay more time?
- Are you expected to show up on site at fixed times set by the contractor, or do you organise your own attendance around the job?
If most answers point towards the employed side, the arrangement warrants a closer look before HMRC makes that assessment for you. If you are comparing CIS treatment with PAYE more broadly, our detailed guide at CIS vs PAYE: a complete comparison sets out the differences in deductions, obligations and rights.
Getting the classification right
Employment status in construction is consistently litigated because many arrangements are genuinely borderline. The practical steps for a contractor to reduce exposure are: run CEST on every new engagement as a starting check; document the real working arrangements rather than relying on contract wording alone; and review long-term exclusive arrangements specifically, because they accumulate risk fastest. Advice before HMRC raises the question is considerably cheaper than defending a reclassification after the fact.
If you want help assessing the employment status of workers currently paid via CIS, or want to check whether your contractor obligations are correctly structured, see our services page.