Register online with HMRC's CIS subcontractor registration service, signing in with the Government Gateway login for your Self Assessment. If you haven't registered as self-employed yet, register for Self Assessment and say you'll work as a construction subcontractor, and HMRC registers you for both. Then give each contractor your name, UTR and National Insurance number exactly as HMRC has them. Once they've verified you, they take 20% instead of 30%. Registering is free.
What 30% costs you
If you aren't registered for CIS, contractors have to take 30% off your labour instead of 20%. You do get the extra back when you file your tax return, but that can be many months later. Meanwhile, it's your money sitting with HMRC.
| Labour in the year | At 20% | At 30% | Extra taken |
|---|---|---|---|
| £25,000 | £5,000 | £7,500 | £2,500 |
| £40,000 | £8,000 | £12,000 | £4,000 |
| £55,000 | £11,000 | £16,500 | £5,500 |
On a typical week of five days at £220, that's £110 more taken off every Friday.
What you need
- Your legal business name. As a sole trader, that's your own name. You can also give a trading name if you use one.
- Your UTR (Unique Taxpayer Reference), which you get when you register for Self Assessment. If you already have one, you'll find it in the HMRC app, in your HMRC online account, or on letters from HMRC.
- Your National Insurance number.
- Your VAT registration number, if you're VAT-registered.
- A Government Gateway login for HMRC online, to register online.
Three ways to register
1. Online, if you're already self-employed
If you've already registered for Self Assessment, use HMRC's online CIS registration service for subcontractors. Sign in with the same Government Gateway details you use for Self Assessment. This is usually the quickest way.
2. At the same time as registering for Self Assessment
If you're new to self-employment, register for Self Assessment as a sole trader and choose the option saying you'll work as a subcontractor in construction. HMRC then registers you for both. HMRC sends your first UTR by post, so allow time before your first job. After that, you can always find it in the HMRC app or your HMRC online account.
3. By post, if you can't go online
Sole traders can fill in form CIS301 and post it to HMRC. It takes longer than registering online. HMRC no longer usually registers subcontractors over the phone.
After you register: getting verified
Registering doesn't change your rate on its own. Each contractor has to verify you with HMRC before paying you, using your name, UTR and National Insurance number. HMRC then tells them which rate to use.
- Tell every contractor you're registered and give them your details, especially if they've already been paying you at 30%.
- Use your name exactly as HMRC has it. If you give a different name, a contractor may not be able to match you and must take 30%.
- Check your first payment statement after verification. It should show 20%.
Still being charged 30%?
- The contractor hasn't verified you again since you registered. Ask them to.
- Your name or UTR doesn't match what HMRC has, for example a nickname or a different spelling.
- Your registration hasn't gone through yet. Check your HMRC online account.
If it still doesn't change, contact HMRC's CIS helpline. Any extra 10% taken while it gets sorted isn't lost. It counts towards your tax bill and comes back through your Self Assessment return. Here's how to claim it.
Gross payment status: 0%
With gross payment status, contractors pay you in full with nothing taken off, and you pay all your tax yourself through Self Assessment. You can apply when you register or later. To qualify, you need to pass three tests:
- Business test: you do construction work (or supply labour for it) in the UK, and your business is run through a bank account.
- Turnover test: at least £30,000 of construction turnover in the last 12 months as a sole trader, not counting VAT and materials.
- Compliance test: you've filed returns and paid your tax and National Insurance on time. Since April 2024, this also covers VAT returns and payments if you're VAT-registered.
HMRC reviews gross status regularly and can take it away if you fall behind. It's good for cash flow, but you have to put money aside for your own tax bill, because nobody else is doing it for you.
Changes you must tell HMRC about
You usually need to register for CIS again (and reapply for gross status if you have it) if you:
- go from sole trader to a partnership, or the other way round
- set up a limited company and work through it
You also need to tell HMRC if you change your trading name or address, or stop trading.
Keeping your rate right in DayGraft
In DayGraft, your CIS rate is set once in Settings: 20%, 30% or 0% for gross status. Every day you log, every weekly statement and every tax-year total uses it. When your registration goes through, change it to 20% and everything you log from then on uses the new rate. Your statements show the deduction clearly, so you can check each contractor is taking the right amount.
Sources (last checked 23 October 2026): What you must do as a CIS subcontractor — GOV.UK · CIS301: register as a sole trader subcontractor — GOV.UK · CIS guide for contractors and subcontractors (CIS340) — GOV.UK · Register for Self Assessment — GOV.UK · HMRC issues guidance on CIS changes (April 2024) — AccountingWEB
This guide is general information, not tax advice. If your situation is complicated, speak to an accountant or HMRC.