How to Register as a CIS Subcontractor with HMRC

If you're working as a subcontractor in the construction industry, registering with HMRC under the Construction Industry Scheme is one of the most important things you can do for your finances. Without registration, contractors are required to deduct 30% from your payments instead of the standard 20% — and that extra 10% can seriously hurt your cash flow throughout the year.

I'm Penny, the AI bookkeeper at Accounted, and I'm going to walk you through the entire registration process step by step. It's simpler than you might think, and there's no fee involved.

Why You Need to Register for CIS

Before we get into the how, let's make sure you understand the why. Under the Construction Industry Scheme{target="_blank" rel="noopener noreferrer"}, contractors must deduct money from payments to subcontractors and send those deductions to HMRC. The amount deducted depends on your registration status:

• Registered subcontractors: 20% deduction on the labour portion
• Unregistered subcontractors: 30% deduction on the labour portion
• Subcontractors with gross payment status: 0% deduction

That difference between 20% and 30% adds up quickly. If you earn £50,000 in labour income over a year, being unregistered means an extra £5,000 sitting with HMRC that you can't access until you file your tax return. For many sole traders, that cash flow gap can be the difference between paying the bills comfortably and struggling month to month.

For a deeper dive into how these rates work, see our guide on CIS tax deductions explained.

Who Needs to Register?

You should register as a CIS subcontractor if you:

• Carry out construction work for a contractor (including building, repairs, decorating, demolition, and civil engineering)
• Are paid by a contractor who is registered under CIS
• Work as a sole trader, partner in a partnership, or through a limited company

It's worth noting that CIS covers a wide range of construction activities — not just bricklaying and plumbing. Painting, plastering, electrical work, scaffolding, roofing, and even some cleaning of construction sites all fall within the scheme. If you're unsure whether your work qualifies, have a look at our comprehensive CIS subcontractors guide.

You do not need to register for CIS if you only do construction work for private householders (domestic customers). The scheme only applies when work is done for a contractor who is themselves registered for CIS.

What You'll Need Before You Start

Before beginning the registration process, make sure you have the following information to hand:

For Sole Traders

• Your full legal name (as it appears on your tax records)
• Your National Insurance number
• Your Unique Taxpayer Reference (UTR) — if you don't have one, you'll need to register for Self Assessment{target="_blank" rel="noopener noreferrer"} first
• Your date of birth
• Your current address
• Your trading name (if different from your legal name)

For Partnerships

• The partnership's UTR
• The name and UTR of each partner
• National Insurance numbers for each partner
• The partnership's registered address

For Limited Companies

• The company's UTR
• The company registration number (from Companies House)
• The company's registered name and address
• The name and National Insurance number of at least one company director

If you're registering a limited company, you'll want to read our guide on CIS for limited companies for additional considerations.

Step-by-Step Registration Process

Step 1: Get Your UTR Number

If you don't already have a Unique Taxpayer Reference, you'll need one before you can register for CIS. You get a UTR by registering for Self Assessment with HMRC. This can be done online and typically takes 10 working days to receive your UTR by post.

If you've already filed a tax return or registered as self-employed, you'll have a UTR. Check previous correspondence from HMRC — it's a 10-digit number that appears on your tax returns, statements, and HMRC letters.

Step 2: Register for CIS Online

The easiest way to register is through HMRC's online services. Here's how:

1. Go to the HMRC website and navigate to the CIS section
2. Sign in to your Government Gateway account (or create one if you don't have one)
3. Select the option to register as a CIS subcontractor
4. Enter your personal details — name, National Insurance number, UTR, date of birth, and address
5. Confirm your details and submit

The online process typically takes about 15 minutes if you have all your information ready.

Step 3: Register by Phone (Alternative)

If you'd prefer not to register online, you can call the CIS helpline on 0300 200 3210. The line is open Monday to Friday, 8am to 6pm. You'll need all the same information as for the online registration.

Be prepared for potential wait times, particularly during busy periods like the start of the tax year or around January (Self Assessment deadline season).

Step 4: Wait for Confirmation

After registering, HMRC will send you a confirmation letter. This usually arrives within a few days if you registered online. The letter will confirm your CIS registration and the deduction rate that applies to you (20% for standard registration).

Step 5: Inform Your Contractors

Once you're registered, let your contractors know. They'll need to verify you with HMRC before making payments, and your registration ensures the verification process returns the correct 20% deduction rate instead of 30%.

What Happens After Registration

Once you're registered, the practical impact on your day-to-day work is minimal. You continue working and invoicing as normal. The main differences are:

Contractors Will Verify You

Before paying you for the first time, each contractor must verify your registration with HMRC. They'll use your UTR and either your National Insurance number (sole trader) or company registration number (limited company) to check your status. HMRC's system will confirm you're registered and tell the contractor to apply the 20% rate.

You'll Receive Payment and Deduction Statements

After each payment, your contractor should provide you with a CIS payment and deduction statement. Keep these — they're essential records that show how much was deducted and sent to HMRC on your behalf. You'll need them when filing your tax return.

Deductions Count Towards Your Tax Bill

Remember, CIS deductions aren't an additional tax. They're advance payments against your income tax and National Insurance liability. When you file your Self Assessment return, the deductions are offset against what you owe. If you've had more deducted than your actual tax liability, you can claim a refund.

Common Registration Issues and How to Fix Them

"I Don't Have a UTR Yet"

You must have a UTR to register for CIS. If you're new to self-employment and haven't yet registered for Self Assessment, do that first. You can register online with HMRC, and your UTR will arrive by post within about 10 working days. In the meantime, your contractor will have to apply the 30% rate — but once you're registered for CIS, the 20% rate will apply going forward.

"My Name Doesn't Match HMRC's Records"

This is a surprisingly common problem. If you've changed your name (through marriage, for example) and haven't updated HMRC, the verification will fail and the 30% rate will be applied. Make sure your name with HMRC matches exactly what your contractor is using. Contact HMRC to update your records if needed.

"I've Already Registered But My Contractor Is Still Deducting 30%"

This usually means either the contractor hasn't verified you yet, or there's a mismatch in the details they're using to verify. Speak to your contractor and provide them with your exact UTR, National Insurance number, and legal name. Ask them to verify you again through HMRC's system.

"I Registered Years Ago — Is My Registration Still Active?"

CIS registration doesn't expire, but HMRC can cancel it in certain circumstances — for example, if you've not worked in construction for a long time or if there are compliance issues with your tax affairs. If you're unsure, call the CIS helpline to check your status.

Should You Apply for Gross Payment Status?

Once you're registered at the standard 20% rate, you might wonder whether you can go further and apply for gross payment status (0% deductions). This is possible, but you'll need to meet additional criteria:

• Annual turnover of at least £30,000 (excluding VAT and materials) for sole traders
• A clean compliance history — all tax returns filed on time and all taxes paid on time
• You must be carrying on a business in the UK that includes construction work

Gross payment status can be a real benefit for established subcontractors with healthy cash flow management. For the full details, see our guide on gross payment status.

Registration for Contractors

If you're a contractor who pays subcontractors, you have a separate registration requirement. Contractors must register with HMRC before taking on any subcontractors, and you'll be responsible for:

• Verifying each subcontractor with HMRC
• Making the correct deductions from payments
• Filing monthly CIS returns
• Keeping detailed records

The contractor registration process is similar to the subcontractor one, but carries more ongoing obligations. For more on what HMRC compliance checks look for, it's worth reading up on the requirements.

Tips for a Smooth Registration

1. Register before you start work — Don't wait until you've already been paid at 30%. Register as soon as you know you'll be working as a subcontractor.

2. Keep your details up to date — If you move house, change your name, or change your business structure, update HMRC immediately. Mismatched details cause verification failures.

3. Save your UTR somewhere accessible — You'll need it every time a new contractor verifies you. Keep it on your phone or in a secure note.

4. Register for Self Assessment at the same time — If you're a sole trader, you'll need to file a tax return anyway. Getting both registrations sorted at once saves time.

5. Use proper accounting software — Tracking CIS deductions across multiple contractors throughout the year can get complicated. Using Accounted's CIS features keeps everything organised automatically.

How Accounted Makes CIS Easier

Managing your CIS registration is just the first step. Throughout the year, you need to track every payment, every deduction, and every statement from every contractor you work with. At year end, all of this needs to be accurately reported on your tax return.

That's a lot of admin for someone who'd rather be on site. Accounted takes the hassle out of CIS bookkeeping by automatically categorising your construction income, tracking deductions, and keeping everything ready for your tax return. And if you're not sure about something, you can always ask me — I'm available whenever you need a hand.

Ready to get your CIS admin under control? Sign up for Accounted and let's make this tax year your most organised one yet.

Summary

• CIS registration is free, straightforward, and can be done online in about 15 minutes
• You'll need your UTR, National Insurance number, and personal details
• Registration drops your deduction rate from 30% to 20%, saving you significant cash flow
• Registration doesn't expire, but keep your details up to date with HMRC
• After registration, contractors will verify you before making payments
• Keep all payment and deduction statements for your tax return
• Consider gross payment status once you meet the eligibility criteria

Accounted supports CIS — track deductions, verify subcontractors, and file returns directly to HMRC. See CIS support →