How to Register for CIS

At Towerstone Accountants we provide specialist CIS accountancy services for contractors and construction businesses across the UK. We created this webpage for subcontractors and contractors who want clear guidance on the Construction Industry Scheme, including registration, deductions, refunds, and ongoing reporting obligations. Our aim is to help you stay compliant with HMRC, avoid costly errors, and understand how CIS affects your tax position.

When I first speak to new construction clients one of the most common issues I uncover is that CIS registration has either been missed entirely or done incorrectly at the start. People are often already working, invoices are being raised, money is being deducted, and yet nobody is fully sure whether they are registered properly or what that registration actually covers.

Registering for the Construction Industry Scheme is not difficult, but it is precise. HMRC expects it to be done at the right time, in the right way, and with the correct status. If you get it wrong it can affect cash flow, trigger higher deductions than necessary, and create problems later when tax returns or refunds are due.

In this article I am going to explain how to register for CIS in clear practical terms. I will cover who needs to register, the difference between contractor and subcontractor registration, how the process works for sole traders and limited companies, what happens after registration, and the mistakes I see most often. By the end you should know exactly what to do and why it matters.

What CIS registration actually means

CIS registration is how HMRC brings construction businesses into the Construction Industry Scheme. It tells HMRC whether you are acting as a contractor, a subcontractor, or sometimes both, and it allows the correct tax treatment to be applied to construction payments.

For subcontractors registration determines the rate of tax deducted from payments. For contractors it creates legal obligations around verification, monthly returns, and paying deductions to HMRC.

CIS registration does not replace Self Assessment, Corporation Tax, or PAYE. It sits alongside them as part of the wider tax system.

Who needs to register for CIS

This is where confusion often starts. Not everyone working in construction needs to register in the same way, but many people do need to register and do not realise it.

You need to register for CIS as a subcontractor if you carry out construction work for a contractor and receive payments where CIS deductions may apply.

You need to register for CIS as a contractor if you pay subcontractors for construction work. This includes not just builders but also developers and certain landlords where construction spend is significant.

Some businesses are both contractor and subcontractor. For example a limited company that takes on subcontract work but also hires other trades to complete projects.

Understanding which role or roles apply to you is essential before you start the registration process.

Registering as a subcontractor

Subcontractor registration is the most common starting point.

If you are a sole trader, partnership, or limited company carrying out construction work for others, you should register as a CIS subcontractor before you start work if possible.

Registration ensures that contractors can verify you correctly and apply the standard 20 percent deduction rate rather than the higher 30 percent rate used for unregistered subcontractors.

From what I see, failing to register early is one of the biggest causes of unnecessary cash flow problems in construction.

Registering as a contractor

Contractor registration is often overlooked, particularly by businesses that do not see themselves as traditional builders.

If you pay subcontractors for construction work you must register as a contractor. This includes property developers, building companies, and in some cases landlords carrying out major works.

Once registered you are legally responsible for verifying subcontractors, deducting CIS where required, submitting monthly returns, and paying deductions to HMRC.

Failure to register as a contractor can result in penalties and backdated obligations.

When you need to register

Timing matters.

Subcontractors should register before starting work or as soon as possible after. Contractors must register before making their first payment to a subcontractor.

HMRC does not accept ignorance as an excuse. If registration is delayed they can still expect deductions and returns to be completed from the correct start date.

How to register for CIS as a sole trader

For sole traders CIS registration is usually done alongside Self Assessment, although the two are technically separate.

You must first be registered for Self Assessment and have a Unique Taxpayer Reference. Without a UTR you cannot register for CIS.

Once you have a UTR you can register for CIS online or by phone. You will need your National Insurance number and details about your business activities.

The process is relatively straightforward and confirmation is usually issued quickly, although it can take longer during busy periods.

How to register for CIS as a limited company

Limited companies must already be registered with Companies House before CIS registration.

You will need the company’s UTR, which is issued by HMRC after incorporation, along with the company registration number.

For limited companies CIS registration links into PAYE even if the company has no employees yet. This catches many people out and can result in unexpected PAYE scheme creation.

In practice I always advise limited companies to take advice before registering to ensure everything is set up cleanly.

Registering for CIS online

The most common method is registering online through HMRC’s systems.

You will need a Government Gateway account. If you already have one for Self Assessment or PAYE you can use the same login.

The system will ask whether you are registering as a contractor, subcontractor, or both. Answering this incorrectly can create issues later so it is important to be clear.

Once submitted HMRC will confirm registration and update your CIS status on their records.

Registering for CIS by phone

Registration can also be completed by phone. This is sometimes preferable where circumstances are more complex or where online access is limited.

HMRC will ask a series of verification questions and confirm details verbally. Follow up confirmation is usually sent by post.

While slower, phone registration can be useful if there are issues with UTRs or business details.

What happens after registration

Once registered as a subcontractor your details are added to HMRC’s CIS system. Contractors can then verify you and apply the correct deduction rate.

As a contractor you will gain access to CIS online services, allowing you to verify subcontractors, submit monthly returns, and view your CIS liabilities.

Registration alone does not trigger deductions or payments. It simply puts the framework in place.

CIS verification and why it matters

Verification is the process contractors use to check subcontractors with HMRC.

When you are verified HMRC confirms your deduction rate. If you are registered this is usually 20 percent unless you have gross payment status.

If you are not registered HMRC instructs the contractor to deduct 30 percent. This is one of the clearest financial reasons to register early.

Gross payment status and CIS registration

When you register as a subcontractor you are not automatically given gross payment status.

Gross status requires a separate application and meeting specific turnover and compliance tests. Registration is simply the first step.

Many people assume registration means no deductions. That is not the case.

CIS registration and VAT

CIS registration is separate from VAT registration.

You can be registered for CIS and not VAT registered, or VAT registered and not CIS registered, depending on your circumstances.

However in construction it is common for both to apply and the interaction between them can affect invoicing and cash flow.

Common registration mistakes I see

The most common issues I deal with include registering under the wrong role, using incorrect UTR details, failing to register for PAYE where required, and assuming a previous employer handled registration.

Another frequent problem is subcontractors starting work before registration and suffering 30 percent deductions for months unnecessarily.

These are avoidable issues but only if registration is taken seriously at the outset.

What if you register late

If registration is late HMRC does not simply ignore the gap.

Contractors may still be required to deduct at the higher rate and HMRC can expect returns and payments to be corrected.

For subcontractors this often means waiting until the Self Assessment return to recover over deducted tax, which can be many months later.

Keeping records after CIS registration

Once registered you must keep proper records.

Subcontractors should keep invoices, CIS deduction statements, and bank records. Contractors must keep verification records, payment details, and copies of monthly returns.

Good record keeping makes tax returns easier and reduces the risk of disputes with HMRC.

CIS registration and Self Assessment

Registering for CIS does not remove the need for a tax return.

Sole traders and partners must still submit Self Assessment returns declaring their full income and expenses, with CIS deductions treated as tax already paid.

I regularly remind clients that CIS is a payment mechanism, not a reporting system.

CIS registration for businesses that stop trading

If you stop trading or stop paying subcontractors you should inform HMRC.

CIS registration does not automatically end when trading stops. Failure to notify can result in nil returns being expected and penalties issued.

Closing CIS properly is just as important as registering correctly.

How long CIS registration lasts

CIS registration does not expire in the same way as a CSCS card.

However HMRC can deactivate registrations if returns are not submitted or if the business becomes inactive. Reactivation can take time and cause disruption.

Keeping your details up to date avoids this.

How I help clients with CIS registration

When I assist clients with CIS registration my focus is on doing it once and doing it properly.

I confirm the correct role, ensure all linked registrations are in place, and check that the business understands its obligations going forward.

This avoids the cycle of corrections, penalties, and refund delays that I see far too often.

Final thoughts

Registering for CIS is one of those steps that feels administrative but has real financial consequences if it is mishandled.

In my experience the people who struggle most with CIS are not those with complex businesses, but those who underestimate the importance of getting registered correctly at the start.

If you take the time to register properly, understand your role, and keep records in order, CIS becomes manageable rather than stressful. It is not something to put off or hope resolves itself, it is a foundation that supports everything else you do in the construction industry.

You may also find our guidance on how to apply for cis and what is cis helpful when dealing with related CIS questions. For a broader overview of CIS rules, compliance, and support, you can visit our CIS guidance hub.