Self Assessment for CIS Subcontractors: What Is Different?

If you work as a subcontractor under the Construction Industry Scheme (CIS) in the UK, you will usually be a sole trader or a business providing construction services to contractors. While you still need to complete a Self Assessment tax return like other sole traders, there are some specific points to be aware of when it comes to your CIS income and tax reporting.

How CIS Affects Your Self Assessment

Under CIS, contractors deduct money from your payments and pass it to HM Revenue and Customs (HMRC) as tax. This deduction is not the final tax you owe but a payment on account. When you fill in your Self Assessment tax return, you must report:

• Your gross income from CIS work — the total amount you earned before any CIS deductions.
• The CIS deductions made by contractors — these are shown on your CIS statements and count as tax already paid.

HMRC uses this information to calculate your overall tax liability. If you owe more tax than the deductions cover, you will pay the difference. If too much tax was deducted, you may receive a refund.

Record-Keeping for CIS Subcontractors

Keeping accurate records is essential. You should keep:

• Copies of all CIS deduction statements from contractors.
• Invoices or payment records showing your gross earnings.
• Receipts and records of allowable business expenses.

These documents help you complete your Self Assessment accurately and support any figures you report if HMRC asks for evidence.

What Is Different from Other Sole Traders?

The main difference for CIS subcontractors is that part of your tax has already been deducted at source by contractors, which you must declare in your return. Other sole traders usually report all income and calculate tax without deductions from third parties.

Also, CIS payments relate specifically to construction work, so income from other sources should be declared separately in your tax return.

Exceptions and Important Notes

• If you are registered for gross payment status under CIS, you receive payments without deductions. You still report your income and pay tax through Self Assessment as normal, but no CIS deductions appear on your statements.
• You must notify HMRC by 5 October after the end of the tax year if you need to complete a Self Assessment tax return, for example if you are newly subcontracting or have not sent a tax return before.
• Failing to file your tax return or pay any tax due by the deadlines can lead to penalties and interest charges.

For detailed guidance on completing your Self Assessment tax return as a CIS subcontractor, consult the official HMRC Self Assessment pages or contact HMRC directly to confirm your specific circumstances.

Official reference: https://www.gov.uk/self-assessment-tax-returns. Always check the latest official guidance. Related forms: Browse our form category.

Important: This article provides general information. Government rules, forms and procedures can change, and this article may not reflect the latest updates. Check current GOV.UK guidance or the relevant authority before relying on it. ITG & Co. is independent and is not affiliated with a government department.