CIS for Contractors: What you really need to know (without the stress)

If you’re a contractor in the construction industry, you’ve probably heard of the Construction Industry Scheme – or CIS. It might sound like a paperwork nightmare, but getting it right is crucial — not just for staying compliant, but for avoiding major headaches and costly penalties.

What Is CIS?

CIS is HMRC’s way of making sure tax is collected on construction work. If you pay subcontractors, CIS applies to you. Under the scheme, contractors deduct money from subcontractors’ payments and send it to HMRC.

It’s not always straightforward to determine what HMRC considers construction work, so it’s important to check carefully and ensure CIS is correctly applied to all relevant subcontractor payments.

What Contractors Need to Do

1. Verify subcontractors. Before paying anyone, check their CIS status with HMRC.
2. Make the correct deductions. Only the labour part of the invoice is subject to CIS. Materials and VAT (if charged) aren’t. Make sure your subcontractors break down their invoices to avoid over-deducting.
3. Register with HMRC. If you pay subcontractors – even occasionally – you need to register as a contractor.
4. Submit monthly returns. Due by the 19th of each month, your return tells HMRC who you paid, how much, and what you deducted.
5. Pay HMRC on time. Any deductions must be passed on promptly.

What Happens If You Get It Wrong?

If you don’t follow CIS rules – like failing to deduct tax when you should, or submitting returns late – HMRC can fine you. Penalties include:

• £100 for a late return – even by one day
• £200 if it’s one month late
• Up to £3,000 or more for serious or repeated failures

And here’s a key point: you’re still liable for deductions, even if you don’t make them. If you overpay a subcontractor by skipping deductions, HMRC will still expect the full amount from you. If you don’t want to be left out of pocket and you don’t want to be chasing subcontractors that you’ve overpaid, make sure you get it right first time around.

Why It Matters

Hiring subcontractors without handling CIS properly can lead to penalties, stress, and unnecessary costs. CIS isn’t as scary as it sounds, and it doesn’t have to be a hassle — but it does need to be done right. Taking the time to understand your responsibilities now can save you a lot of trouble (and money) later.

The information contained within this publication is given by way of general guidance. Specialist advice should always be sought in relation to your particular circumstances. No liability is accepted by Ensors for any actions taken without seeking appropriate professional advice.