What Is a CIS Return

Learn what a CIS return is, who needs to submit it, when it's due and what information it must include under the Construction Industry Scheme.

What Is a CIS Return?

If you work in the UK construction industry as a contractor, you are required to submit regular CIS returns to HMRC. These returns form a core part of the Construction Industry Scheme (CIS) and ensure that tax is properly collected from payments made to subcontractors. Failing to understand or submit these returns correctly can result in fines, interest charges and loss of compliance status.

In this guide, we explain what a CIS return is, who needs to complete it, how often it must be submitted and what information it should include.

What Is a CIS Return?

A CIS return is a monthly report submitted by a contractor to HMRC, detailing all payments made to subcontractors for construction work in that tax month. It includes the amount paid, the tax deducted, and information about each subcontractor.

The return ensures that HMRC is kept informed of how much tax has been deducted from subcontractors under the scheme. It is a legal requirement for all businesses registered as contractors under CIS.

Who Must Submit a CIS Return?

You must submit CIS returns if you are a contractor who pays subcontractors for construction work. This includes:

  • Construction companies

  • Property developers

  • Businesses that spend more than £3 million on construction within a 12-month period

  • Non-construction businesses acting as contractors on major building projects

If you are a subcontractor only, you do not submit CIS returns. Instead, you receive CIS deduction statements from the contractors who pay you.

What Information Goes Into a CIS Return?

A typical CIS return includes the following details:

  • The subcontractor’s name

  • The subcontractor’s Unique Taxpayer Reference (UTR)

  • Whether the subcontractor is paid with gross payment status or subject to 20 percent or 30 percent deduction

  • Total amount paid to the subcontractor (excluding VAT)

  • Amount of tax deducted (if any)

  • Details of any materials costs provided by the subcontractor (which are not subject to tax deduction)

You also need to confirm:

  • That the subcontractors listed are self-employed

  • That you have verified each subcontractor with HMRC

  • That the information provided is accurate to the best of your knowledge

When Do You Need to Submit a CIS Return?

CIS returns must be submitted monthly to HMRC by the 19th of the following month. For example, if you paid subcontractors during April, the return for that period must be submitted by 19 May.

If the 19th falls on a weekend or public holiday, the deadline is not extended.

Late submissions or incorrect returns may result in:

  • Automatic penalties starting at £100

  • Interest charges on unpaid deductions

  • HMRC compliance checks and potential suspension from the CIS

How Do You Submit a CIS Return?

There are several ways to submit a CIS return:

  1. Online through HMRC’s website using your Government Gateway account

  2. Using CIS-compliant accounting or payroll software

  3. Through your accountant or payroll provider

If you have not paid any subcontractors during a month, you must still file a nil return. You can do this online or via your software. If you stop using subcontractors permanently, you must inform HMRC to avoid ongoing return requirements.

What Happens After You Submit?

Once your CIS return is submitted:

  • HMRC calculates how much you owe based on the deductions reported

  • You must pay the total amount deducted from subcontractors to HMRC by the 22nd of the month (or 19th if paying by post)

  • Each subcontractor must be given a CIS payment and deduction statement, showing how much has been deducted for their records

These statements are vital for subcontractors to claim back overpaid tax through Self Assessment or Corporation Tax returns.

Keeping Records

Contractors must keep records of all:

  • Subcontractor invoices

  • CIS returns

  • Deduction statements

  • Verification numbers from HMRC

  • Materials costs and breakdowns

These records must be retained for at least three years after the end of the tax year they relate to. HMRC may request to see them during an inspection or enquiry.

Final Thoughts

A CIS return is a legal reporting requirement for any business that pays subcontractors for construction work. It ensures HMRC receives accurate information about tax deductions and helps subcontractors manage their own tax responsibilities.

Submitting your returns on time and with the correct information is essential for avoiding penalties and staying compliant. Whether you handle it in-house or use an accountant, getting the CIS return process right will keep your construction business running smoothly and protect you from unnecessary costs.