If your UK business uses subcontractors in the construction industry, you must follow the Construction Industry Scheme (CIS) rules set by HMRC. This includes registering as a contractor, making deductions from payments and submitting monthly returns.
Failure to comply can lead to penalties, so it is essential to understand the requirements. This guide explains the key steps for early-stage founders and e-commerce sellers who may engage subcontractors for building, fitting-out or maintenance work related to their operations.
What is the Construction Industry Scheme (CIS)?
The Construction Industry Scheme is a tax deduction scheme operated by HMRC. It applies to payments made by contractors to subcontractors for construction work, including labour, materials and certain other services. The scheme helps ensure that tax is collected on payments at source.
CIS covers a wide range of activities such as building, demolition, site preparation, installation of fixtures and repair work. Even if your main business is e-commerce or retail, using subcontractors for warehouse fit-outs, shop refurbishments or office alterations can bring you within the scheme. Rules change over time, so always check the current GOV.UK guidance.
Deciding If You Need to Register as a Contractor
You must register as a contractor with HMRC if you pay subcontractors for construction work. This applies whether you are a limited company, partnership or sole trader. Registration is required even if you only use subcontractors occasionally.
To decide if CIS applies, review the type of work being carried out. Examples include installing shelving in a warehouse, building an extension to a storage unit or carrying out repairs to business premises. If the work falls under construction, register before making the first payment. Use the HMRC online service to register; the process requires your business details and confirmation of the work types.
Registering Subcontractors and Verifying Their Status
Before paying any subcontractor, you must verify their CIS registration status. HMRC provides an online verification tool where you enter the subcontractor's details. The system will confirm whether they are registered and tell you the correct deduction rate.
Keep records of every verification. Subcontractors can be registered as gross (no deduction), net (standard deduction) or higher rate. You should ask new subcontractors for their Unique Taxpayer Reference and check their status each time before payment. This step protects you from incorrect deductions and helps demonstrate compliance if HMRC makes enquiries.
Making Deductions and Issuing Statements
When paying a registered subcontractor, deduct the appropriate percentage from the amount due, excluding VAT. The deducted amount must be paid to HMRC. Provide the subcontractor with a written statement showing the gross payment, the deduction made and the net amount paid.
Accurate record-keeping is essential. Maintain details of each invoice, the verified CIS rate, the calculation of the deduction and the date of payment. These records must be kept for several years. If a subcontractor is not registered with CIS, you must apply the higher rate deduction. Rates and thresholds can change, so refer to current HMRC tables before each payment run.
Submitting Monthly CIS Returns
You must submit a CIS return to HMRC every month, even if no payments were made. The return declares all subcontractors used, the total payments made and the total tax deducted. The deadline is 14 days after the end of each tax month.
Use HMRC's online portal or compatible accounting software to file. Late or missing returns trigger automatic penalties. If your business has no subcontractors in a particular month, you still file a nil return. Set calendar reminders for the 19th of each month (the effective deadline for electronic filing) to avoid missing submissions.
Penalties for Non-Compliance
HMRC can charge penalties for failing to register, incorrect deductions, late monthly returns or failure to keep proper records. Penalties increase with repeated failures and can be based on the potential lost revenue or the seriousness of the breach.
Common issues include submitting returns after the deadline, using the wrong deduction rate or not verifying subcontractors. You can reduce or avoid some penalties by making a voluntary disclosure as soon as an error is discovered. Keep evidence of your processes, such as dated verification screenshots and payment records, to support your position in any HMRC review.
Practical Steps to Stay Compliant
1. Review all current and planned supplier relationships to identify any that involve construction work.
2. Register as a contractor on GOV.UK before the first relevant payment.
3. Verify every subcontractor using the HMRC online service and record the outcome.
4. Calculate and deduct the correct amount for each invoice, issue statements and pay the tax to HMRC by the 22nd of the following month.
5. Submit accurate monthly returns on time, using software that integrates with HMRC where possible.
6. Retain all records for at least six years and review your processes annually.
Consider using specialist payroll or accounting software that automates CIS calculations and reminders. If your business grows and you regularly use subcontractors, speak to an accountant familiar with construction schemes. At Loomworks in Liversedge, early-stage founders can access mentoring that includes guidance on basic compliance topics such as this.
Frequently asked questions
Do I need to register for CIS if I only use a subcontractor once?
Yes. If you pay for construction work, even on a one-off basis, you must register as a contractor with HMRC before making payment. A single payment can trigger the requirement to operate CIS, submit returns and make deductions.
What records do I need to keep for CIS?
You must keep verification confirmations, subcontractor invoices, deduction calculations, payment records, monthly returns and statements given to subcontractors. These should be retained for several years in case of HMRC enquiries.
Can I avoid penalties for late CIS returns?
Penalties are usually automatic for late filing. You can appeal if you have a reasonable excuse, or make a voluntary disclosure promptly if you discover an error. Consistent timely filing is the best way to avoid penalties.
Does CIS apply to e-commerce businesses?
It applies if you pay for construction work such as fitting out premises, building storage facilities or carrying out repairs. The nature of the work, not your main business activity, determines whether CIS rules must be followed.
How do I know which deduction rate to apply?
Use the HMRC verification service to check each subcontractor's status. It will confirm whether to deduct at the standard rate, higher rate or make no deduction. Always verify before payment and keep the confirmation.
Related reading: National Minimum Wage Rules for Company Directors, Auto-Enrolment Pension Duties for Small Employers, Health and Safety Responsibilities for Home-Based Businesses. Browse all company admin & legal guides or apply to Loomworks.