Construction Industry Scheme Knowledge Base
Clear, practical guides to the Construction Industry Scheme (CIS) — covering contractor and subcontractor obligations, deductions, returns, and HMRC compliance. Every article references official GOV.UK and HMRC sources.
Your complete guide to the Construction Industry Scheme — 22 articles covering CIS fundamentals, registration, deduction rates, monthly returns, subcontractor tax, and compliance.
CIS Fundamentals
What Is the Construction Industry Scheme?
How CIS works, why it exists, and who it applies to.
Contractors vs Subcontractors
The definitions, obligations, and key differences under CIS.
Construction Operations: What Is In Scope?
Which types of work fall inside and outside CIS.
Deemed Contractors
When non-construction businesses must operate CIS.
Registration
Registering as a CIS Contractor
How and when to register with HMRC as a CIS contractor.
Registering as a CIS Subcontractor
Why registering reduces your deduction rate from 30% to 20%.
Gross Payment Status
The turnover, compliance, and business tests for 0% deductions.
The CIS Verification Process
How contractors verify subcontractors with HMRC before payment.
Deductions & Payments
CIS Deduction Rates (20%, 30%, 0%)
The three CIS deduction rates and when each applies.
Materials Deductions Under CIS
How materials costs reduce the amount subject to CIS deductions.
Calculating CIS Deductions
Step-by-step worked examples of CIS deduction calculations.
Paying CIS Deductions to HMRC
When and how to send CIS deductions to HMRC.
Returns & Reporting
Monthly CIS Returns (CIS300)
What to include in your monthly CIS return and how to file it.
CIS Filing Deadlines
Monthly, quarterly, and annual deadlines for CIS compliance.
Correcting CIS Errors & Amendments
How to fix mistakes on previously submitted CIS returns.
CIS Nil Returns
When and how to submit a nil return if you had no subcontractor payments.
Subcontractor Tax
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