CIS Registration UK (2026): What Contractors and Subcontractors Need to Know Before You Register

Why was CIS created in the first place?

CIS exists because, for years, parts of the construction industry had a big problem.

A lot of work was paid quickly, often through layers of subcontractors, and a lot of that income was not declared properly.

That created two issues:

• Tax evasion: people getting paid but not reporting earnings
• Fraud chains: supply chains set up to look legitimate, but where money is moved through multiple parties and tax is not paid correctly

So CIS was created to collect tax earlier, reduce under-reporting, and make payments traceable.

That is why CIS works by having deductions taken before the subcontractor submits their tax return.

CIS is not “only for subcontractors”

This is where most people get it wrong.

CIS is used by:

Contractors

You are a contractor if you:

• Pay subcontractors for construction work, even if construction is not your main business
• Need to verify subcontractors
• Must submit regular CIS returns

Subcontractors

You are a subcontractor if you:

• Get paid to carry out construction work
• Have CIS deductions taken from your labour charges (unless paid gross)

Many businesses are both

This is common in real life.

Example:
You do jobs for larger contractors, but you also bring in labourers for your own projects.

In that case, you may need to register for CIS as contractor and subcontractor, so you can get paid correctly and pay others correctly.

If you want to register as contractor and subcontractor in one go, you can do it through a service that handles it properly.

When do you actually need to register?

You usually need CIS registration when:

• You are starting construction work as a subcontractor and want to avoid higher deductions
• A contractor asks you for verification details before they pay you
• You are paying other trades or labour for construction work
• You want your payments and deductions handled cleanly for tax time

If you leave it too late, you might still get paid, but it can cost you in deductions and delays.

The CIS deduction rates (this affects your cashflow)

When a contractor pays a subcontractor under CIS, a deduction rate is applied.

There are three main outcomes:

• 0% deduction if you have Gross Payment Status
• 20% deduction if you are registered as a subcontractor
• 30% deduction if you are not registered

That 30% rate is what catches people out.

It is not a fine, but it hurts cashflow and it can take time to recover through your tax return.

Getting CIS set up early can stop you losing 30% from your payments.

Contractor duties: what you must do once registered

If you register as a contractor, CIS comes with monthly admin that you cannot ignore.

As a contractor, you usually need to:

• Verify subcontractors before paying them
• Apply the right deduction rate
• Keep records of labour and deductions
• Submit CIS returns on time
• Pay deductions to HMRC

Even if you are a small contractor, or only pay subcontractors sometimes, you can still have these obligations.

This is why many construction businesses register as contractor early, even if they only plan to subcontract work occasionally.

If you are paying subcontractors soon, it is worth setting up CIS properly before the first invoice.

Subcontractor side: what changes once you are registered

If you register as a subcontractor:

• Contractors can verify you correctly
• You usually move to the 20% deduction rate
• Your deductions count as tax already paid (in most cases)
• Your records are cleaner for Self Assessment or Corporation Tax

Important point: CIS does not replace your normal tax return. It affects how tax is collected, not whether you owe tax.

What is Gross Payment Status and should you apply?

Gross Payment Status means contractors pay you with 0% CIS deductions.

That can be useful if you:

• Have high costs
• Want smoother cashflow
• Are running a limited company with strong records

But it is not automatic.

Approval depends on factors like compliance history and meeting certain tests. Many subcontractors start with standard registration first, then consider gross status later once everything is stable.

Not sure if you should start standard or go for gross payment status? A registration service can guide you based on your setup.

How to register for CIS in the UK (realistic explanation)

You can register for CIS directly with HMRC.

The problem is that the registration process often includes:

• jargon-heavy questions
• confusing category choices (contractor, subcontractor, or both)
• no practical support if you are unsure
• a higher chance of mistakes that cause delays later

That is why many construction business owners:

• ask their accountant to do it, or
• use an online service that handles it correctly

Online Filings helps you register for CIS without needing to figure out the technical wording yourself. It suits people who want it done properly, without wasting time.

If you would rather avoid the jargon and get it done correctly the first time:

Common mistakes that cause delays or higher deductions

Here are the issues we see most often:

• Registering as subcontractor only, then later needing contractor status urgently
• Getting paid before registration and ending up on 30% deductions
• Giving contractors the wrong details and failing verification
• Not understanding what counts as labour vs materials on invoices
• Forgetting monthly contractor returns and building up problems

If you are registering as both, most of these issues are avoidable.

Final checklist (for contractor + subcontractor registration)

Before you register, make sure you have:

• Your business details correct (name, structure, trading details)
• Tax references (UTR and related info depending on your setup)
• A clear idea if you are paying subcontractors, getting paid as a subcontractor, or both
• A plan for handling CIS returns if you are a contractor

Want a simple way to register for CIS without the admin headache?

Online Filings can handle CIS registration for contractors and subcontractors, so you can get back to running your jobs.