Right to Work Checks for Subcontractors: A Legal Guide for UK Main Contractors

What is a Right to Work check?

A Right to Work check is the process by which an employer — or, in a labour supply chain, a contractor — verifies that a person has the legal right to work in the United Kingdom before that person carries out any work. The obligation derives from the Immigration, Asylum and Nationality Act 2006, which makes it a civil and criminal offence to employ someone who does not have the right to work in the UK.

A common misconception in construction runs the other way: that this obligation is a strict binary that either always or never applies to subcontractors. In reality, it's more nuanced. Home Office guidance is that Right to Work checks are not required to establish a statutory excuse where an individual is genuinely self-employed and engaged under a contract for services. That carve-out has real limits, though. It doesn't extend to labour-supply and agency arrangements, umbrella companies, sponsored workers, or cases where the self-employed label doesn't reflect the genuine substance of the relationship, and the Home Office can look behind the label a contractor puts on an engagement. Because self-employment status can be challenged or reclassified after the fact, and because the consequences of getting it wrong are severe, many main contractors check every subcontractor's Right to Work status regardless of engagement structure, treating it as standard risk management rather than a strict legal minimum.

Whether the Right to Work obligation applies to a specific person you pay for construction work depends on the nature of that engagement. Where it does apply, the practical question that matters is whether you have the evidence to demonstrate you discharged it, which is why many contractors check as standard practice rather than trying to categorise every engagement first.

Which documents are accepted?

The Home Office divides acceptable Right to Work documents into two lists. List A documents establish a permanent, unrestricted right to work and require no follow-up check. They include: a UK passport (current or expired), an Irish passport or Irish passport card, a UK birth or adoption certificate accompanied by a document showing the worker's National Insurance number (such as a P45, P60, or National Insurance card), and a Biometric Residence Permit (BRP) that is endorsed 'indefinite leave to remain' or 'no time limit'. Where a List A document is seen, copied, and retained, that single check covers the entire period of the engagement — there is no obligation to re-check.

List B documents establish a time-limited right to work and require follow-up checks when the document expires. They include: a Biometric Residence Permit with an expiry date, and a visa in a current or expired passport alongside a Home Office letter confirming the worker retains an ongoing right to work. Where a List B document is accepted, you must diarise the expiry date and carry out a fresh check before that date. Failure to re-check at expiry removes the statutory excuse that the original check provided.

Share codes apply to EU, EEA, and Swiss nationals who entered the UK under the EU Settlement Scheme. These individuals hold their right to work status digitally — they cannot prove it with a physical document, and you cannot accept a physical document from them as a valid check. Instead, the worker provides a share code, which you must check together with the worker's date of birth via the Home Office online checking service at gov.uk/view-right-to-work. The result page confirms their status in real time. This is the only valid method of checking EU Settlement Scheme holders, and it is the employer's responsibility to carry out the online check — not to rely on a screenshot or printout provided by the worker themselves.

How do you carry out a valid check?

In-person check — The check must happen before work starts, not on the first day and not after the subcontractor has begun. There is no grace period. The steps are: see the original document in person; check that it is genuine and has not been tampered with; check that the person presenting the document is its rightful holder (compare the photograph and any personal details against the person in front of you); make a clear copy of the document and note the date on which the check was carried out. The copy can be a photocopy or a digital photograph taken at the time of the check. If the document has information on both sides — as a Biometric Residence Permit does — copy both sides.

Online check for share codes — Go to gov.uk/view-right-to-work. Enter the share code provided by the worker and the worker's date of birth. The result page will display their right to work status, any conditions attached to it, and the date until which it is valid. Take a screenshot or print the result page — this is your record. Do not rely on the worker's own screenshot; you must run the check yourself.

How long do you need to keep the records?

For each Right to Work check you carry out, you must retain: a clear copy of the document you checked (both sides if the document carries information on the reverse — the photo page and any relevant visa pages of a passport are sufficient; you do not need every page); the date on which the check was carried out; and the name of the person who carried out the check. These three elements together form the record that gives you a statutory excuse.

For share code checks, the record is the printout or screenshot of the gov.uk result page, which includes the worker's name, their right to work status, and the date the check was run. Keep this alongside a note of who ran it.

The retention period is the full duration of the engagement, plus two years after the engagement ends. So if you engaged a subcontractor from June 2025 to March 2026, you must keep their Right to Work records until at least March 2028. This mirrors the approach to other compliance records and is long enough to cover any Home Office investigation that might arise from work carried out during the engagement.

Both physical and digital storage are acceptable. Digital records with a reliable timestamp are strongly preferred in practice — they are easier to retrieve quickly during an inspection, harder to lose, and the timestamp provides independent evidence of when the check was carried out. A compliance platform that stores records with an immutable audit trail is the most defensible approach.

What are the penalties for not checking?

The civil penalty for employing an illegal worker is up to £45,000 per illegal worker for a first offence. If you receive a civil penalty and commit the same offence again within three years of the first penalty, the rate doubles: up to £60,000 per worker for a repeat offence. These penalties apply per worker, not per incident — if you have five workers on site without valid checks, the exposure is multiplied accordingly.

The criminal exposure is more serious still. If you knowingly employed someone without the right to work — or had reasonable cause to believe they did not have the right to work, which since the Immigration Act 2016 includes the situation where you simply failed to check — you can be prosecuted. On conviction, the maximum sentence is five years' imprisonment and an unlimited fine. The "reasonable cause to believe" standard means that not checking is not a neutral act; it is the act that creates the criminal exposure.

The statutory excuse is the mechanism that protects you. If you carry out a valid check before work starts and retain the evidence, you have a statutory excuse in respect of that worker — meaning the Home Office cannot impose a civil penalty on you, even if it later turns out that the worker had no right to work and had deceived you with false documents. The excuse requires both the check and the retained record. Without the record, there is no excuse, regardless of what you recall doing. The record is your only protection, and it needs to exist before work starts.

Does this apply to self-employed subcontractors?

It depends on how they're engaged, and this is genuinely one of the more complex areas of Right to Work compliance. Treat what follows as a starting point, not a final answer. The statutory excuse mechanism in the Immigration, Asylum and Nationality Act 2006 is built around the employer/employee relationship. Home Office guidance is that Right to Work checks are not required to establish a statutory excuse where an individual is genuinely self-employed and engaged under a contract for services rather than a contract of employment. If a subcontractor invoices you as a sole trader, controls how and when they carry out the work, and bears their own commercial risk, they may fall outside the direct statutory-excuse requirement.

That said, several situations bring the obligation back into scope even where a subcontractor describes themselves as self-employed. Labour-supply and agency arrangements are one: where workers are supplied to you by a labour agency or gangmaster, Right to Work obligations typically sit with whichever party in the chain is treated as the employer for that purpose. It's worth confirming in writing who that is and that they are actually carrying out checks. Umbrella companies and similar intermediary arrangements are another. Sponsored workers are a third, since sponsor duties apply regardless of self-employed status. Genuine self-employment status itself isn't guaranteed simply because someone is CIS-registered or invoices you: HMRC and employment tribunals can and do reclassify working relationships that don't reflect genuine self-employment in substance, and if that happens, obligations you assumed didn't apply may turn out to have applied all along.

Because of that uncertainty, many main contractors check every subcontractor's Right to Work status regardless of how they're engaged. This isn't because the law strictly demands it in every case, but as a risk-management practice, and sometimes because main contract terms or client requirements impose checking obligations that go beyond the statutory minimum. Given how much turns on the specific facts of each relationship, this is an area worth getting advice on from a qualified immigration solicitor for your specific subcontractor arrangements. The Home Office's Employer's Guide to Right to Work Checks is a useful starting reference, but it should be read alongside, not instead of, advice tailored to your situation.