SiteIt's Sunday night. The main extruder's down with a drive fault and your controls engineer is on holiday. You ring round and get a contract engineer booked for 10pm.
They turn up on time. Security signs them in. Then someone in the office asks a question nobody can answer. Has anyone checked their right to work?
The agency thinks you did. You think the agency did. Nobody ever asked the engineer.
Right to work checks on cover staff go wrong in exactly this way. Everyone assumes it's someone else's job. And since 1 October 2026 the rules reach further than they used to.
Whose check is it?
Start with the usual case. You ring an agency, they send an engineer, and that engineer works on your site under your direction.
The Home Office guide covers this almost word for word. Its example is a manufacturing company that takes temporary workers from an employment business during a busy spell. Liability for illegal working "remains with the employment business" as the employer of those workers (Employer's guide to right to work checks, Example 12).
So the agency does the check. But you're not off the hook on knowing it's done. Under the Conduct Regulations, an agency can't supply anyone until it has confirmed the authorisations the law requires for the job (regulation 19). GOV.UK's guidance for agencies spells it out: "An authorisation required by law includes the right to work in the United Kingdom" (Conduct Regulations guidance). We cover the rest of what an agency owes you in what the Conduct Regulations mean when you take an agency engineer.
Our view: ask for it in writing every time. A line in the booking confirmation that says "right to work checked" costs the agency nothing.
What changed on 1 October
Until this month, the scheme was built around employees. Now it has been extended to "worker's contracts, individual subcontracting arrangements and certain online matching services" (Employer's guide, Annex C). For those newer arrangements, a civil penalty can only apply where the work started on or after 1 October 2026.
Two lines in the guide matter for anyone booking contract engineers.
First, the label doesn't decide it. The guide says the scheme applies to the substance of the arrangement, "rather than the label given to it". Calling someone a contractor proves nothing.
Second, your IR35 decision doesn't settle it either. The guide calls an IR35 determination "a tax assessment" that doesn't decide right to work duties. If you've been through your status decision as a hirer, that's a separate job.
Booking an engineer direct
This is where most sites are unsure. You've found a good sole trader electrician, or one who runs a small limited company, and you book them yourself.
Some of these fall outside the scheme. The guide's example is a plumber who runs their own business and works for lots of customers: "A right to work check is not required" (Example 5). A client that contracts with someone's personal service company for a project doesn't need to check either (Example 6).
But there's "no blanket exclusion" just because someone works through a PSC. An engineer who turns up week after week, works your rota and takes orders from your shift manager looks a lot like a worker.
Here's where we land. If you can't say for sure the engineer is out of scope, do the check. It takes ten minutes. Arguing about status after a Home Office visit takes a lot longer.
Doing the check properly
GOV.UK lists the routes (checking a job applicant's right to work):
- an online check, if the engineer gives you a share code
- a manual check of the original documents
- an identity service provider using document checking technology
British and Irish citizens can't get a share code, so for them it's the original passport or passport card, or an identity service provider.
Do it before the work starts. The guide is clear that the check comes "before employment commences" if you want the defence it gives you, which it calls a statutory excuse. Record the date you did it in the form the guide asks for, and keep the copies securely "for the duration of the worker's employment and for two years* afterwards".
Then diarise the follow-up. If the engineer has time-limited permission, you check again "on, or before" the date it ends. Settled status needs no follow-up.
One more rule. Check everyone the same way. The guide tells employers to be consistent "regardless of nationality or perceived immigration status". Checking only the engineer with the foreign accent is discrimination, and it gives you no defence.
If you sell maintenance on to someone else
Most factories and warehouses buy cover for their own site, and the extended rules don't touch them. But some readers run maintenance contracts for clients and fill them with subcontracted engineers.
That's a chain, and the guide treats it differently. Where you're contracted to deliver work to a third party and pass it down a chain, you "may be treated as the employer" of the people doing the work (Example 7). To protect yourself you need a written statement in place before the work starts. It must require right to work checks down the chain, ban subcontracting without your consent, and give you audit rights (Employer's guide, section 3).
What it costs to get wrong
The penalty is "a civil penalty of up to £60,000* per illegal worker". In serious cases there's a prison sentence of up to five years.
There's a smaller cost that bites first. If the check hasn't been done and the engineer can't show you anything, you send them home. The extruder is still down, and every hour waiting for a replacement is an hour of lost output. If you've never priced that, work out what an hour of downtime costs you before the next Sunday night.
If you're the engineer reading this, we've written what to have ready as a contractor.
What to do on Monday
- Ask every agency you use to confirm in writing that right to work is checked for each engineer they send.
- List the engineers you book direct. For each one, decide if they're in scope. If you can't tell, check them.
- Set up a folder with the check date, the copies and any permission end dates, and a diary reminder for each follow-up.
- If you subcontract maintenance work for clients, get your written statement in place before the next job starts.
* The civil penalty figure and the two-year record-keeping period are correct as of 18 October 2026. Check the Employer's guide to right to work checks for the latest.