Every year, thousands of workers from Poland, Romania, Portugal, India, and dozens of other countries come to the UK and start working on construction sites. Most are paid through the Construction Industry Scheme. And most lose more money than they need to — not because CIS is unfair, but because nobody explained the steps they need to take before their first payment.

The system is the same for everyone. CIS doesn't care about your nationality. But the registration process is longer for non-UK nationals because you need to obtain documents that UK-born workers already have: a National Insurance number, a UTR, and then CIS registration. Miss any of these steps, and your contractor deducts 30% instead of 20% from every payment.

This guide covers the entire process, in order, from the day you arrive to the day you claim your first refund.

Before Anything Else: Your Right to Work

Before you can register for anything — NI number, UTR, CIS — you must have the legal right to work in the UK. This is not optional and it is not just a formality. Your contractor is legally required to check your right to work before hiring you.

Step 1: Get Your National Insurance Number

Your National Insurance number (NI number or NINO) is a unique identifier that HMRC uses to track your tax and National Insurance contributions. UK-born residents receive one automatically before they turn 16. If you've come from abroad, you need to apply for one.

1. Go to gov.uk and search for "apply for a National Insurance number".
2. Complete the online application — you'll need your passport or national identity card, your visa or Biometric Residence Permit (BRP), and evidence that you're working, have a job offer, or are actively seeking work.
3. Prove your identity — HMRC will email you instructions. You may need to post copies of documents or attend an appointment.
4. Wait for your NI number — HMRC sends it by post. It can take up to 16 weeks after you prove your identity.

Step 2: Get Your UTR (Unique Taxpayer Reference)

Once you have your NI number, you can register for Self Assessment. This is how HMRC issues your UTR — the 10-digit number that identifies you for tax purposes and is required for CIS registration.

1. Go to gov.uk and register for Self Assessment as self-employed.
2. Create a Government Gateway account if you don't have one.
3. Complete the registration — you'll need your NI number, full name, address, and details about your construction work.
4. HMRC sends your UTR by post within 10 working days (up to 21 days if your registered address is abroad).

Step 3: Register for CIS

Having a UTR does not automatically register you for CIS. This is a separate step — and the one that drops your deduction from 30% to 20%.

1. Log in to your HMRC account via Government Gateway.
2. Go to the Construction Industry Scheme section.
3. Register as a subcontractor.
4. Give your contractor your UTR and NI number — they verify you with HMRC before making payments.

Once verified, your deduction rate drops to 20%. The entire process typically takes a few working days after you submit the registration.

The Timeline: How Long Does It All Take?

Here's the realistic timeline for a non-UK national starting from scratch:

During those 4–5 months, you can work — but you'll be deducted at 30%. Every payment at 30% instead of 20% is money you'll get back when you file Self Assessment, but you won't see that money until your return is processed. That's why starting the NI application immediately after arriving in the UK matters — every week of delay is another week at the higher rate.

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What to Do If You Worked at 30% Before Registering

This is the most common situation for non-UK nationals. You arrive, start working, and your contractor deducts 30% because you're not CIS-registered yet. Months later, you get your NI number, your UTR, and your CIS registration — and now you're at 20%. But what about all those months at 30%?

The answer: you claim it all back through Self Assessment. When you file your tax return at the end of the tax year, you enter your total gross income and your total CIS deductions (from all your payment and deduction statements). HMRC calculates your actual tax liability and refunds the difference.

If you were deducted at 30% for six months and 20% for six months, the overpayment from the 30% period is included in your refund. You don't need to do anything special — it's all handled through the same Self Assessment process.

Documents You Need to Keep

• CIS payment and deduction statements — from every contractor, for every payment. Photograph them immediately and save digitally.
• Your invoices — every invoice you issued, showing labour and materials separately.
• Expense receipts — tools, materials, mileage, PPE, insurance, phone, training.
• Bank statements — showing CIS payments received.
• Passport / visa / BRP copies — for your own records (contractors also keep copies).
• Your UTR and NI number — saved in your phone or a secure location.

What If You Leave the UK?

If you return to your home country — temporarily or permanently — you should still file a UK Self Assessment for any tax year in which you worked in the UK. CIS deductions taken during your time here are offset against your UK tax liability, and any overpayment is refunded to your UK bank account.

You can file your Self Assessment from abroad using HMRC's online service — you just need your Government Gateway login. If you've lost access, call the Self Assessment helpline on 0300 200 3310 to recover your credentials.

Gross Payment Status: The 0% Rate for Established Subcontractors

Once you've been working in the UK for several years and built up a track record, you may qualify for gross payment status (GPS) — meaning 0% CIS deduction. You receive the full invoice amount and settle your tax through Self Assessment.

To qualify, you must pass HMRC's three tests: a UK-based construction business with a UK bank account, net construction turnover of at least £30,000 per year, and a clean compliance record (all tax returns filed on time, all tax paid on time). GPS is worth pursuing once you're established — on £50,000 turnover, the difference between 20% and 0% is £10,000 in annual cash flow.

Umbrella Companies: What Non-UK Nationals Need to Know

When you first arrive in the UK, some agencies and contractors may tell you to work through an umbrella company instead of registering as self-employed under CIS. This is a different arrangement — and it changes your tax position significantly.

Under an umbrella company, you are technically an employee of the umbrella. The umbrella invoices the contractor, deducts PAYE tax and National Insurance from your pay, and pays you a net salary. You are not self-employed, you are not on CIS, and you cannot claim self-employed business expenses through Self Assessment.

If you want to work as a self-employed CIS subcontractor (which gives you more control over expenses and potentially a higher take-home through refunds), you need to register independently with HMRC — NI number, UTR, CIS — and invoice contractors directly. If you're going through an umbrella, the umbrella handles everything, but you lose the ability to claim self-employed expenses.

Common Mistakes Non-UK Nationals Make with CIS

• Not applying for an NI number immediately — every week of delay is another week at 30% deduction. Apply the moment you arrive and have evidence of right to work.
• Assuming the UTR is enough for CIS — getting a UTR and registering for CIS are two separate steps. Without CIS registration, you stay at 30%.
• Not keeping deduction statements — especially at the start when everything is new. These are your proof of tax paid. Without them, no refund.
• Not filing Self Assessment — if you don't file, your CIS deductions stay with HMRC forever. You will almost certainly be owed a refund. File even if you've left the UK.
• Working for cash without CIS — some contractors offer to pay cash and skip CIS. This is illegal for the contractor and leaves you with no tax record, no proof of income, and no refund rights.
• Closing their UK bank account before the refund arrives — keep it open until HMRC has processed your return and paid your refund.

Your Complete Checklist — Non-UK National Working Under CIS

• Confirm you have the right to work in the UK (visa, settled status, BRP)
• Apply for a National Insurance number immediately — gov.uk, online
• Check your BRP — your NI number may already be on the back
• Start work while waiting for NI number (with proof of right to work)
• Once NI number arrives, register for Self Assessment at gov.uk → UTR in 10 days
• Register for CIS using your UTR — separate step, takes a few days
• Give your UTR and NI number to every contractor
• Keep every CIS payment and deduction statement — photograph immediately
• Keep all expense receipts for tools, travel, PPE, materials
• File Self Assessment after 5 April — claim your refund
• If leaving the UK, file P85 and keep your bank account open