How to Register for CIS as a Subcontractor (2025/26)

CIS registration is one of the first things to sort out if you're working as a subcontractor in the construction industry. Without registering for CIS with HMRC, contractors deduct 30% from your payments instead of 20% — meaning you lose an extra 10% of every invoice to tax deductions. You'd then need to wait until your Self Assessment to reclaim the difference.

This guide walks you through the registration process, what you need before you start, and what happens after you're registered.

Why CIS Registration Matters for Subcontractors

CIS registration is the process of signing up with HMRC so that contractors deduct tax at 20% rather than 30% from your construction payments. It isn't technically compulsory — you can work as an unregistered subcontractor — but the financial impact of not registering is significant.

Status	Deduction rate	Payment on a £1,000 invoice
Registered	20%	£800
Unregistered	30%	£700
Gross payment status	0%	£1,000

On £50,000 of annual labour income, the difference between registered (20%) and unregistered (30%) is £5,000 in extra deductions. You'd eventually get that money back through Self Assessment, but in the meantime it's cash you can't use.

Registration is free and takes about 15 minutes online. For a detailed breakdown of all three rates, see our guide on CIS deduction rates.

What You Need Before Registering for CIS

Before you can register for CIS, you need two things from HMRC:

1. A Unique Taxpayer Reference (UTR)

Your UTR is a 10-digit number that HMRC uses to identify you for tax purposes. If you've ever filed a Self Assessment tax return, you already have one.

Where to find your UTR:

• Previous Self Assessment tax returns
• Letters from HMRC (look for a 10-digit number)
• Your HMRC online account (Personal Tax Account)

If you don't have a UTR yet, you'll need to register for Self Assessment first. More on this below.

2. A National Insurance Number

Your NI number is on your payslips, P60, or any letters from HMRC or DWP. If you can't find it, you can find your National Insurance number through your personal tax account on GOV.UK.

Additional Information You'll Need

Depending on your business structure, have the following ready:

• Sole traders: Your legal name, trading name (if different), business address, and trading start date
• Partnerships: Partner details and partnership UTR
• Limited companies: Company Registration Number and company UTR
• VAT-registered businesses: Your VAT registration number

Step 1: Register for Self Assessment and Get a UTR

If you're new to self-employment and don't have a UTR, you need to register for Self Assessment first. You can do both at once — when you register for Self Assessment online, select "working as a subcontractor in the construction industry" and HMRC will register you for both Self Assessment and CIS simultaneously.

To register for Self Assessment:

1. Go to Register for Self Assessment on GOV.UK
2. Create a Government Gateway account (or sign in to your existing one)
3. Select that you're self-employed
4. When asked about your work, choose subcontractor in the construction industry
5. Complete the form with your personal and business details
6. Submit the registration

What happens next:

• HMRC sends your UTR by post — this typically takes up to 10 working days
• You'll also receive an activation code for your online account
• Once you have your UTR, your CIS registration is already active if you selected the subcontractor option

Important: Until your UTR arrives, contractors are required to deduct at the 30% rate because they can't verify you with HMRC. Plan ahead and register before you start working if possible.

Step 2: Register for CIS Online Through Government Gateway

If you already have a UTR from Self Assessment but haven't registered for CIS yet, you can register for CIS online as a separate step.

Online registration:

1. Go to Register as a CIS subcontractor on GOV.UK
2. Sign in with your Government Gateway user ID and password
3. Enter your UTR, National Insurance number, and business details
4. Confirm your details and submit

HMRC processes the registration and activates your UTR under the CIS scheme. This typically takes a few working days.

By phone:

If you prefer not to use the online service, call the CIS helpline on 0300 200 3210 (Monday to Friday, 8am to 6pm). Have your UTR and National Insurance number ready.

By post:

Download and complete the appropriate registration form from GOV.UK:

• CIS301 — Sole trader registration
• CIS304 — Partnership registration
• CIS305 — Company registration

Post the completed form to the address on the form. Postal registration takes longer than online — allow several weeks.

Step 3: Share Your UTR for Contractor Verification

Once you're registered, every contractor you work for needs to verify your CIS status with HMRC before they can pay you at the 20% rate.

What to give your contractor:

• Your full legal name (as registered with HMRC)
• Your UTR
• Your National Insurance number

The contractor enters these details into HMRC's online verification system. HMRC confirms your registration status and tells the contractor which deduction rate to apply. Each verification generates a reference number that appears on your CIS payment statement.

Tip: Write down your UTR and keep it somewhere accessible. You'll give it to every new contractor you work for.

What Happens After CIS Registration

After completing your CIS registration, your day-to-day work doesn't change much — but the paperwork side matters:

• Contractors deduct 20% instead of 30% from your payments
• You receive payment statements showing the gross amount, materials deducted, CIS deduction, and net payment
• You file a Self Assessment return each year to declare your income and reclaim any overpaid CIS
• HMRC credits your CIS deductions against your income tax and National Insurance bill

If your CIS deductions exceed your actual tax liability for the year, HMRC refunds the difference. Many subcontractors receive refunds — see our guide on how CIS works for a worked example.

Common CIS Registration Problems and How to Fix Them

"I registered but my contractor is still deducting 30%"

This usually means the contractor hasn't verified you yet, or verified you before your registration was processed. Ask your contractor to re-verify your details with HMRC. If the problem persists, call the CIS helpline on 0300 200 3210.

"I can't find my UTR"

Check your HMRC Personal Tax Account online, look at old Self Assessment returns or HMRC correspondence, or call HMRC on 0300 200 3310 to request it. They'll post it to your registered address.

"I registered for Self Assessment but wasn't asked about CIS"

You can add CIS registration separately after the fact. Follow the online registration steps in Step 2 above using your existing UTR.

"My name doesn't match what's on HMRC's records"

Verification fails if the name your contractor gives HMRC doesn't match your registered name. If you've changed your name, update it with HMRC first. Use your legal name (as on your passport or driving licence), not a nickname or trading name.

CIS Subcontractor Registration Checklist

Use this to track your progress:

1. Get a UTR — register for Self Assessment if you don't have one (allow 10 working days)
2. Find your National Insurance number — check payslips, P60, or your personal tax account
3. Register for CIS — online, by phone, or by post
4. Wait for confirmation — HMRC processes your registration within a few working days
5. Share your details — give your UTR and NI number to each contractor
6. Check your first payment statement — confirm the 20% rate is being applied

Frequently Asked Questions

How long does CIS registration take?

If you already have a UTR, online registration typically takes a few working days to process. If you need a UTR first, allow up to 10 working days for it to arrive by post, plus a few more days for the CIS registration to activate.

Can I register for CIS if I'm also employed?

Yes. Many subcontractors have a PAYE job alongside their CIS work. CIS registration only applies to your construction subcontractor income. Your employment income continues to be taxed through PAYE as normal.

Do I need to register separately for each contractor?

No. You register for CIS once with HMRC. Each contractor then verifies your status individually, but your single registration covers all your CIS work regardless of how many contractors you work for.

What's the difference between CIS registration and gross payment status?

CIS registration gives you the standard 20% deduction rate. Gross payment status is a separate application that lets you receive payments with no deductions (0%). It has stricter requirements, including a clean tax compliance history and minimum annual turnover of £30,000 for sole traders (2025/26).

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This guide is for informational purposes only and does not constitute tax, legal, or financial advice. Tax rules change frequently. Always verify current requirements on GOV.UK or consult a qualified accountant for your specific situation.

Official Sources

• What you must do as a CIS subcontractor — GOV.UK
• How to register as a CIS subcontractor — GOV.UK
• Construction Industry Scheme (CIS) — GOV.UK
• Register for Self Assessment — GOV.UK
• Find your National Insurance number — GOV.UK