If you are starting work as a subcontractor in the UK construction industry, one of the first things you should do is register with HMRC under the Construction Industry Scheme. Being registered means contractors deduct 20% tax from your payments instead of 30%, which immediately improves your cash flow and makes it easier to claim a rebate at the end of the tax year.

At R&R Chartered Certified Accountants, we help new and existing subcontractors across Lancashire register correctly and avoid the common mistakes that delay payments or reduce rebates. This guide walks you through the registration process step by step.

CIS Registration: Why You Should Register for CIS

Registering for CIS is not optional if you want to be paid correctly by most contractors. Once registered, HMRC tells contractors to deduct tax at the lower 20% rate rather than the default 30%.

The difference is significant. On a £2,000 invoice for labour, an unregistered subcontractor loses £600 upfront, while a registered subcontractor loses £400. Over a year, that extra 10% can amount to thousands of pounds tied up with HMRC until you file your self assessment tax return.

Who Needs to Register?

You should register as a CIS subcontractor if:

• You do construction work for a contractor.
• You are self-employed, a partner in a partnership, or the owner of a limited company.
• You work in a trade covered by CIS, such as building, plumbing, electrical work, plastering, roofing, groundwork or decorating.

If you are a limited company, the company registers separately. If you are self-employed, you register as an individual under your Unique Taxpayer Reference.

What You Need Before You Register

Before starting the registration, make sure you have:

• Your National Insurance number.
• Your Unique Taxpayer Reference if you already file a tax return.
• Your business name, trading address and contact details.
• The date you started working as a subcontractor.

If you have not yet registered for self assessment, you should do that first or at the same time.

How to Register Online

1. Go to the HMRC online services page and sign in or create a Government Gateway account.
2. Navigate to the Construction Industry Scheme registration section.
3. Enter your personal or business details, including your National Insurance number and UTR.
4. Confirm that you are registering as a subcontractor.
5. Submit the registration and wait for HMRC confirmation, which usually arrives within a few working days.

You can also register by phone or post if you cannot use the online service. Once registered, HMRC will send you a verification number that contractors may ask for.

What Happens After Registration?

Once registered, HMRC will confirm your status. You should then:

• Tell any contractors you work for that you are CIS-registered.
• Provide your UTR and National Insurance number when asked.
• Keep all CIS payment and deduction statements.
• Make sure your self assessment tax return is filed each year to claim any rebate.

Common CIS Registration Mistakes

• Registering too late: Contractors may deduct 30% from your first payments if registration is delayed.
• Using the wrong entity: A sole trader and a limited company are registered differently.
• Missing the self assessment link: CIS registration does not replace self assessment registration.
• Not keeping statements: You need these to prove deductions and claim rebates.
• Trying to register as a contractor only: If you hire subcontractors, you may need both statuses.

You can complete the process on the official HMRC CIS subcontractor registration page. If you are not yet registered as self-employed, start with registering for Self Assessment on GOV.UK.

Frequently Asked Questions

Final Thoughts

CIS registration is one of the simplest ways to improve your cash flow as a subcontractor. The 10% difference between registered and unregistered deductions adds up quickly, and being registered also makes it easier to claim your annual rebate.

If you need help registering for CIS, setting up self assessment or understanding how the scheme affects your tax, contact R&R Chartered Certified Accountants for a free consultation. We work with subcontractors across Blackburn, Lancashire and the North West every day.

WRITTEN BY

Rehan Razzaq, FCCA

Founder, R&R Chartered Certified Accountants

ACCA Chartered Certified and Xero Certified Advisor, helping UK small businesses and subcontractors with accounts, tax and financial planning since 2021.

More about Rehan →