How to Register for CIS as a Subcontractor
Why You Must Register for CIS
If you work as a subcontractor in the UK construction industry, registering for CIS with HMRC is one of the most important steps you can take. Without registration, contractors are required to deduct 30% from your payments instead of the standard 20%. That 10% difference adds up quickly.
On £40,000 of annual labour income, the difference between 20% and 30% deductions is £4,000 held back from your cash flow. You would eventually reclaim it through Self Assessment, but in the meantime, that is money you cannot use for materials, wages, or day-to-day expenses.
What You Need to Register
Before you contact HMRC, make sure you have the following information ready:
- Your National Insurance number — found on your payslip, P60, or official HMRC correspondence
- Your Unique Taxpayer Reference (UTR) — a 10-digit number issued when you registered for Self Assessment. If you have not yet registered for Self Assessment, you will need to do that first
- Your legal name — as it appears on your HMRC records
- Your business details — trading name (if different from your legal name), business address, and the type of construction work you do
- Your date of birth
If you are registering a limited company, you will also need the company registration number from Companies House.
How to Register: Step by Step
Option 1: Online via HMRC
The fastest way to register is through HMRC's online service:
- Go to the HMRC CIS online service on GOV.UK
- Sign in with your Government Gateway credentials (or create an account if you do not have one)
- Select the option to register as a subcontractor
- Enter your personal details, UTR, and National Insurance number
- Provide your business details and the types of construction work you carry out
- Submit the registration
HMRC will confirm your registration, usually within a few days. You will receive a letter confirming your CIS registration status.
Option 2: By Phone
Call the CIS helpline on 0300 200 3210. You will need all the same information as for online registration. The helpline is open Monday to Friday, 8am to 6pm.
Phone registration can be completed in a single call, and HMRC can often verify you immediately so you know your deduction rate straight away.
What Happens After Registration
Once registered, you are in the CIS system. When a contractor verifies you with HMRC before making a payment, HMRC will confirm that you are registered and should have 20% deducted (rather than 30%).
You do not receive a CIS registration card or certificate. The verification process is entirely digital — contractors check your status online or by phone.
Your Obligations as a Registered Subcontractor
- Keep accurate records of all income and CIS deductions
- Retain all CIS payment and deduction statements from contractors
- File your Self Assessment tax return by the deadline (31 January following the end of the tax year)
- Claim your CIS deductions against your tax bill on your Self Assessment
- Inform HMRC of any changes to your business details
Can You Register for Gross Payment Status at the Same Time?
Yes. When you register as a subcontractor, you can apply for Gross Payment Status at the same time. However, GPS has additional requirements — you need to meet turnover and compliance tests. If you are a new business, you may not qualify for GPS immediately but can apply later once you meet the criteria.
What If You Are Already Registered for Self Assessment?
If you are already registered with HMRC for Self Assessment (which you should be as a self-employed person), you still need to separately register for CIS. Self Assessment registration and CIS registration are different things. However, the process is straightforward and you can do both through the same Government Gateway account.
Registering a Partnership or Limited Company
Partnerships
Each partner must be individually registered for CIS, and the partnership itself must also be registered. Each partner needs their own UTR and National Insurance number.
Limited Companies
The company is registered for CIS using its company UTR and Companies House registration number. Directors do not need to register individually as subcontractors (the company is the subcontractor), but the company must have a UTR before it can register for CIS.
Common Registration Problems
UTR Not Yet Issued
If you have recently registered for Self Assessment, your UTR may take up to 10 working days to arrive by post. You cannot register for CIS without it. If it has been more than 10 days, contact HMRC to chase it up.
Details Do Not Match HMRC Records
If the details you provide during registration do not match what HMRC has on file, your registration may be delayed. Check that your name and National Insurance number are exactly as HMRC knows them. If you have changed your name, update HMRC records first.
Already Registered Without Knowing
If you previously worked in construction and registered for CIS, you may still be registered. Check your HMRC online account or call the CIS helpline to confirm your current status.
How Accounted Helps After Registration
Once you are registered, Accounted helps you stay on top of your CIS obligations:
- Track deductions automatically — Penny identifies CIS payments in your bank feed
- Store statements digitally — no more paper statements to lose
- Calculate your refund — see how much you are owed throughout the year
- File your Self Assessment with all CIS data ready to go
Take a look at our pricing plans to find the right fit.
Get registered, get organised, get refunded. Sign up for Accounted and let Penny keep your CIS records in perfect order.
Tax & Compliance Specialists
Our tax specialists have decades of combined experience in UK sole trader and small business taxation, MTD compliance, and HMRC submissions. All content is reviewed against current HMRC guidance before publication and updated quarterly to reflect legislative changes.
Ready to try Accounted?
Join UK sole traders who are simplifying their bookkeeping and tax.
Start your 14-day free trial