TL;DR Using subcontractors lets you take on more work without taking on employees. But without a clear system, things go wrong fast. This guide covers how to vet subcontractors properly, what to put in a written agreement, what the Construction Industry Scheme means for you as the one paying, and how to share jobs without handing over access to your whole business.
Bringing in a subcontractor should make your life easier. More often than not, it doesn't. At least not straight away.
A missed job detail. A subcontractor who turned up not knowing the full scope. A customer who got two different answers from two different people working on the same job. UK small businesses lose an average of 24 working days a year to admin, and poor subcontractor management is one of the biggest contributors for tradespeople running jobs across multiple workers.
The good news: most of these problems aren't subcontractor problems. They're communication and organisation problems. And they're fixable with the right habits and the right subcontractor management software.
This guide covers everything you need to manage subcontractors well: how to check them out before they start, what to agree in writing, what CIS means for your tax position, and how to share job information without giving away access to every customer you've ever worked with. It also links to our broader guide on job management software for tradespeople if you want to see how the right tool ties all of this together.
Why do tradespeople use subcontractors?
Most tradespeople bring in subcontractors for one of three reasons: they've got more work than they can handle alone, a job needs a skill they don't have, or they want flexibility without the commitment of taking on staff.
All three are good reasons. Subcontracting lets you say yes to bigger jobs. It lets a plumber bring in a tiler to finish a bathroom. It lets an electrician get a plasterer in to make good after first fix. You get the right person for each part of the job, and you stay in control of the customer relationship.
Around 36% of UK trade businesses report struggling to find permanent staff, which makes subcontracting even more valuable as a flexible model. You're not alone in relying on it.
The challenge isn't whether to use subcontractors. It's how to manage them well once you do.
What should you check before taking on a subcontractor?
Before you hand a job to a subcontractor, check three things: their experience and references, their insurance cover (they need their own public liability), and that their availability lines up with your programme. A written agreement before work starts protects both sides.
This sounds obvious, but it's easy to skip steps when you're busy. A quick phone call to a previous contractor they've worked for is worth the ten minutes. You're not just checking they can do the work. You're checking they're reliable, they communicate, and they don't leave jobs half-finished.
On insurance: your own employer's liability policy won't cover subcontractors. They need their own public liability insurance. Ask to see it. If they can't provide it, don't use them. If something goes wrong on site and they're not covered, the problem lands with you.
The Federation of Master Builders recommends checking availability for the full duration of the work, not just the start date. A subcontractor who's double-booked halfway through a job causes more disruption than not having them at all.
What should a subcontractor agreement cover?
At minimum, a written agreement should state the scope of work, the price, the programme (start date and expected duration), and who is responsible if work needs to be redone. It doesn't need to be long. It needs to be clear.
A lot of tradespeople skip this step, especially with subbies they've worked with before. That's understandable. But a clear written record protects both parties if anything goes sideways. It's not about distrust. It's about having something to refer back to.
A solid subcontractor agreement should also cover confidentiality and payment terms, including what happens if payment is late. If your subcontractor has access to your customer's details or site photos, you want it agreed in writing that those stay with you.
Include a defects liability period too. If the work needs to be corrected after completion, your agreement should specify that the subcontractor rectifies it at their own cost. One paragraph. It saves significant arguments later.
You don't need a solicitor for every job. But for regular subcontractors or larger projects, it's worth getting a template reviewed once.
What is CIS and does it apply to you?
If you pay a subcontractor for work that falls under the Construction Industry Scheme (CIS), you're required to register with HMRC as a contractor and deduct tax from their labour payments before you pay them. This applies to most building and trade work. If you don't register, HMRC can fine you.
CIS is HMRC's system for collecting tax from subcontractors in the construction and trades industry. It applies to work including installation of systems like plumbing, heating and electrical, as well as decoration, groundwork, roofing, scaffolding and more.
Here's how the deductions work. You deduct tax from the labour portion of what you pay your subcontractor before handing over the money. You then pay that deduction to HMRC. The rates are:
The 30% rate is a strong incentive for both sides to get registered. As a sole trader paying subcontractors, you're required to file monthly CIS returns with HMRC detailing those payments and deductions. Missing these returns leads to penalties.
One important point: CIS deductions apply to labour only, not materials. If your subcontractor charges you for both, make sure the invoice separates the two clearly.
You can register as a contractor on HMRC's Construction Industry Scheme pages. If you're uncertain whether CIS applies to your specific situation, speak to an accountant. The rules are clear for most trades work, but the detail matters for your tax position.
If you use subcontractors for invoicing and payment work, our guide on how to invoice as a tradesperson is worth reading alongside this one.
Can you work with the same subcontractors long-term?
Yes. There's no legal limit on how long you can work with the same subcontractors. The issue isn't duration. It's whether HMRC could argue they're actually employees. As long as they're genuinely self-employed and you have clear agreements in place, you can use the same subbies for years.
A lot of tradespeople worry about a so-called 13-week rule. It doesn't exist for subcontractors. It comes from Agency Worker Regulations, which apply to agency workers, not self-employed subbies. You can stop worrying about that one.
What HMRC does look at is whether your subcontractor is genuinely self-employed. The key questions are practical. A self-employed person has control over how, when and where they do the work, can take on other clients, and isn't paid through PAYE. If your subcontractor works only for you, follows your instructions like an employee, and uses all your equipment, HMRC may decide they're not really self-employed.
The fix is straightforward: keep the relationship clearly subcontracted. Use written agreements. Let them work for other people. Don't give them employee-level supervision. And make sure your agreement reflects how the working relationship actually operates.
If you're using a trusted subcontractor for job management for electricians or job management for plumbers, the same principles apply regardless of trade.
How do you share jobs with subcontractors without losing control?
Sorting out the legal and admin side is one thing. The day-to-day operational challenge is different: once a subcontractor is on a job, how do you keep the customer record accurate, the job status up to date, and the right information in front of the right people?
The most common approach is WhatsApp groups, forwarded texts, and photos in someone's camera roll. It works until it doesn't. A job update that only one person sees. A site photo no one can find. A customer who rings asking for an update and nobody has a clear picture of where things stand.
The better approach is to share the job itself, not your whole business.
With Trader, you can share a specific job with a subcontractor without giving them access to your full customer list or any other jobs. They see what they need: the job details, any site photos, the current status. You stay in control of everything else.
You control exactly what each person can see. A subcontractor on one job doesn't see your estimates on another. A partner with full access sees everything. You set the access levels, and you can change them at any time.
This is what Trader's job sharing features are built around. Good subcontractor management software lets you share exactly what a subcontractor needs to see, without giving them access to jobs that aren't theirs.
The short version
Using subcontractors well comes down to a few straightforward habits.
Check references and insurance before anyone starts. Get the scope, price, and programme agreed in writing. Understand your CIS obligations before you make the first payment. Keep the working relationship clearly subcontracted if you plan to use the same people long-term. And use a tool that lets you share jobs without sharing everything.
None of this is complicated. But it does need to be done. The jobs that go wrong with subcontractors almost always come back to one of these steps being skipped.
Trader keeps job information in one place and lets you share it on your terms. One simple monthly price. Full access. No complicated permissions setup.
Frequently asked questions
Do I need to register for CIS if I only use subcontractors occasionally?
Yes, if the work falls under CIS. The scheme applies based on the type of work, not how often you use subcontractors. If you make even one payment to a subcontractor for qualifying construction or trade work, you need to be registered as a contractor with HMRC. Register through the HMRC Construction Industry Scheme pages before you make the first payment. If you're unsure whether your work qualifies, speak to an accountant.
What insurance does a subcontractor need to have?
At minimum, your subcontractor needs their own public liability insurance. Your employer's liability policy covers your employees, not subcontractors. If something goes wrong on site and your subcontractor isn't insured, you could find yourself liable. Ask to see their certificate before work starts. For subcontractors carrying out design work, professional indemnity insurance is also worth checking.
Can I share just one job with a subcontractor without giving them access to my other customers?
Yes, with Trader. You can share a specific job with a subcontractor and control exactly what they can see: job details, site photos, and status updates. They don't get access to your full customer list or any other jobs. You set the access level and can adjust it or remove it at any time.
What's the difference between a subcontractor and an employee in the eyes of HMRC?
The key question is control. A subcontractor is genuinely self-employed: they decide how, when and where the work gets done, they can work for other clients, and they're responsible for their own tax. An employee works under your direction and is paid through PAYE. If your subcontractor looks like an employee in practice but isn't treated as one, HMRC may reclassify them. That means backdated tax and National Insurance contributions fall on you. Keep the relationship clearly subcontracted and document it in writing.
How do I keep track of what a subcontractor has done on a job?
The simplest method is a shared job record that both of you can update. With Trader, a subcontractor you've shared a job with can update the job status, add site photos, and log notes in real time. You see everything they add as soon as they add it. No chasing for updates. No photos buried in someone's phone.
