REMEZ & PARTNERS

Registering for CIS

Register as self-employed first — that produces your UTR — then register separately under the Construction Industry Scheme as a subcontractor, using the same UTR and your National Insurance number. Registered subcontractors have 20% deducted from their labour instead of 30%. Registration is free.

Two registrations, not one — and the gap between them is why so many subcontractors are still losing 30% months after they thought they had sorted it.

The two registrations

  1. Register as self-employed with HMRC. This is what puts you into Self Assessment and produces your Unique Taxpayer Reference. The deadline is 5 October after the tax year you started in — seeregistering as a sole trader for the detail.
  2. Register under CIS as a subcontractor, using that same UTR and your National Insurance number. This is the step that gets you verified at 20% rather than 30%.
  3. Give each contractor the details you registered with — the exact name, not a trading name you invented later.
  4. Collect the payment and deduction statements. Contractors must issue them monthly. Without them, proving what was deducted becomes your problem rather than theirs.

Why 30% keeps coming off

Every contractor verifies you with HMRC before paying you. Verification matches the name, UTR and National Insurance number they submit against HMRC's record. Anything that does not match returns an unverified result, and an unverified subcontractor is deducted at 30%.

The usual causes, in order of frequency:

  • A trading name given instead of the registered name.
  • A digit wrong in the UTR — ten digits, easily transposed.
  • Registered as self-employed but never registered under CIS.
  • A limited company verified against the director's personal UTR instead of the company's.

All four are fixable in a phone call, and all four cost you 10% of your labour for every week they are not.

Getting 30% deducted?

Send us a payslip and your registration details. We will tell you why it is happening, fix the verification, and work out what is recoverable from the months already deducted.

Or send an email

Free assessment first. If there is work to do, you get a fixed quote in writing before anything starts.

What happens after you register

Nothing changes about how you work. Contractors deduct 20% from the labour element of your invoices — not from materials, and not from VAT — and pay it to HMRC against your name. At the year end your tax return reconciles those deductions against what you actually owe once expenses and the £12,570 personal allowance are taken into account, which is normally where the refund comes from.

If your business grows to the point where the cash-flow cost of deductions matters,gross payment status removes them entirely.

Questions people ask

Do I have to register for CIS?

Registration is not compulsory, but the alternative is expensive: unregistered subcontractors are deducted at 30% instead of 20%. The extra is not lost — it comes back through your tax return — but you are lending HMRC an additional tenth of your labour for up to a year.

Is CIS registration the same as registering as self-employed?

No, they are two separate steps and you need both. Registering as self-employed puts you into Self Assessment and produces your UTR; CIS registration then tells HMRC to verify you at the lower deduction rate. Doing the first and forgetting the second is the most common reason 30% keeps coming off.

My contractor still deducts 30% after I registered. Why?

Almost always a verification mismatch: the name, UTR or National Insurance number the contractor entered does not match what HMRC holds. Give them exactly what you registered with — the trading name you use day to day is often not it.

What if I work for several contractors?

You register once. Every contractor then verifies you separately with HMRC before the first payment, and each should give you a monthly payment and deduction statement. Keep all of them: they are your evidence of what was deducted.

Do I register if I use a limited company?

Yes, the company registers as a subcontractor in its own right, using its own UTR. The deductions are then set against the company's liabilities rather than your personal tax — a different mechanism with its own paperwork, and one worth setting up properly from the start.

What if I have been working on CIS for years without registering?

You have been overpaying at 30% and can claim the difference back through the returns for those years. Register now, then file what is outstanding. If returns were never filed at all, that is worth sorting before HMRC raises it rather than after.

Figures are for the tax year shown and change every April. They are general information, not advice — we check the current position for your circumstances before anything is filed.

Reviewed 19 October 2026.

Part of our work on cis and construction — if you want someone to take it off your hands, start with our CIS accountant page.