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CIS Deemed Contractor: Does Your Business Count?

The Accounted Tax Team·17 March 2026·4 min read

What Is a Deemed Contractor?

A deemed contractor is a business that is not primarily in the construction industry but still has to operate CIS because of the amount it spends on construction work. If your business spends more than £3 million on construction operations in any rolling 12-month period, you become a deemed contractor and must comply with CIS rules.

This is a point many businesses miss. You might run a retail chain, a hotel group, a housing association, or a property investment company — and still fall within CIS if your construction spending exceeds the threshold.

Who Typically Becomes a Deemed Contractor?

Property Developers

If you develop properties and pay subcontractors for construction work, you are likely a deemed contractor — or even a mainstream contractor if construction is your core activity.

Housing Associations

Housing associations regularly commission building and maintenance work. Many exceed the £3 million threshold.

Retailers and Hospitality Businesses

Large retail chains and hotel groups that carry out shopfitting, refurbishment, or expansion work often spend more than £3 million on construction over a 12-month period.

Local Authorities and Government Bodies

These are automatically within CIS regardless of spending levels.

Industrial and Commercial Businesses

Factories, warehouses, and office-based businesses that undertake significant building work may qualify.

The £3 Million Threshold

The threshold is based on your total expenditure on construction operations over any rolling 12-month period. This includes:

  • Payments to subcontractors for construction work
  • Construction-related costs even if paid to companies

The £3 million figure includes VAT. It is assessed on a rolling basis — you do not need to exceed it in a financial year specifically; any consecutive 12-month period counts.

What Counts as Construction Operations?

The same activities that fall within CIS generally:

  • Building, demolition, and alterations
  • Repairs and decorating
  • Civil engineering
  • Installing heating, ventilation, power, lighting, and water systems
  • Roadworks and landscaping (when part of construction)

What Does Not Count?

  • Professional services (architecture, surveying, project management)
  • Material supply without installation
  • Manufacturing off-site
  • Carpet fitting
  • Scaffolding hire without labour

Your Obligations as a Deemed Contractor

Once you become a deemed contractor, your obligations are the same as any CIS contractor:

  1. Register with HMRC as a CIS contractor
  2. Verify all subcontractors before making payments
  3. Deduct the correct percentage from subcontractor payments
  4. Submit monthly CIS returns to HMRC
  5. Pay deductions to HMRC by the monthly deadline
  6. Issue payment and deduction statements to subcontractors
  7. Keep records for at least six years

How to Know If You Have Crossed the Threshold

Review your accounts for the past 12 months and identify all payments made for construction work. Include:

  • Direct payments to subcontractors
  • Payments to construction companies
  • Invoices from builders, electricians, plumbers, and other trades

If the total exceeds £3 million, you are a deemed contractor and must register with HMRC.

If you are approaching the threshold, plan ahead. Registration takes time, and you will need systems in place to verify subcontractors and process deductions before making further payments.

Common Mistakes

1. Not Realising You Qualify

Many non-construction businesses do not monitor their construction spending against the £3 million threshold. This can lead to operating outside CIS when they should be within it — resulting in retrospective charges and penalties.

2. Not Registering in Time

If you cross the threshold, you must register before making further subcontractor payments. Payments made without CIS deductions could make you liable for the deductions that should have been made.

3. Treating All Suppliers the Same

Not all payments to construction-related businesses require CIS deductions. Payments for materials only, professional services, or exempt work do not fall within CIS. You need to assess each payment.

How Accounted Helps Deemed Contractors

Even if construction is not your core business, Accounted can manage your CIS obligations:

  • Construction spend tracking — monitor your spending against the £3 million threshold
  • Subcontractor management — verification records, deduction rates, and payment history
  • Monthly returns — CIS data prepared and ready for filing
  • Compliance reminders — Penny keeps you on top of deadlines

Visit our pricing page to find the right plan.


Do not get caught out by deemed contractor rules. Sign up for Accounted and let Penny manage your CIS obligations, even if construction is not your main business.

TagsCISdeemed contractorHMRCconstructioncompliance
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The Accounted Tax Team

Tax & Compliance Specialists

Our tax specialists have decades of combined experience in UK sole trader and small business taxation, MTD compliance, and HMRC submissions. All content is reviewed against current HMRC guidance before publication and updated quarterly to reflect legislative changes.

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