Last updated: February 2026
CIS accounting explained for contractors can often feel confusing — especially for trades businesses dealing with subcontractor deductions, HMRC reporting requirements, and VAT obligations.
In this guide, we break down how the Construction Industry Scheme (CIS) works in the UK, how deductions are calculated, and what contractors and subcontractors need to record properly in 2026.
What Is the Construction Industry Scheme (CIS)?
The Construction Industry Scheme (CIS) is an HMRC scheme that applies to contractors and subcontractors in the construction sector.
Under CIS:
- Contractors deduct money from subcontractor payments.
- Deductions are passed to HMRC.
- Subcontractors treat these deductions as advance tax payments.
CIS applies to most construction-related work, including:
- Building and repairs
- Plumbing and electrical installation
- Groundworks
- Demolition
- Decorating
- Site preparation
Full official guidance is available from HMRC.
CIS Deduction Rates
As of 2026, the standard deduction rates are:
- 20% – For registered subcontractors
- 30% – For unregistered subcontractors
- 0% – For subcontractors with gross payment status
Contractors must verify subcontractors before applying the correct deduction rate.
How CIS Accounting Works for Contractors
If you are a contractor:
You must:
- Register for CIS
- Verify subcontractors
- Deduct the correct percentage
- Submit monthly CIS returns
- Provide payment and deduction statements
- Keep accurate digital records
Failure to submit monthly returns can result in penalties.
CIS deductions do not include:
- Materials
- VAT
- Certain allowable expenses
Understanding what is deductible is essential for correct accounting.
How CIS Works for Subcontractors
If you are a subcontractor:
- CIS deductions are not additional tax.
- They count as advance payments towards Income Tax and National Insurance.
- You may receive a refund if too much is deducted.
Accurate bookkeeping is critical to ensure:
- Deductions are properly recorded
- Tax returns reflect correct amounts
- Cash flow remains manageable
CIS and VAT
CIS and VAT operate separately.
However, VAT-registered contractors must still:
- Submit VAT returns under Making Tax Digital
- Record CIS deductions properly
- Ensure VAT is calculated on the correct amounts
This is where accounting software becomes particularly useful for trades.
Common CIS Mistakes Tradespeople Make
- Failing to verify subcontractors
- Incorrect deduction percentages
- Missing monthly return deadlines
- Poor record keeping
- Confusing CIS deductions with VAT
These mistakes can lead to penalties and cash flow problems.
Why Good Accounting Software Matters for CIS
Managing CIS manually in spreadsheets increases the risk of:
- Miscalculated deductions
- Late submissions
- Poor reporting visibility
Modern accounting software designed for trades can:
- Track CIS deductions automatically
- Generate compliant reports
- Improve accuracy
- Reduce administrative workload
If you’re comparing platforms, see our full guide to the best accounting software for trades.
Detailed Example: How CIS Deductions Work in Practice
Let’s look at a simple example.
A contractor hires a registered subcontractor to complete electrical installation work worth £5,000.
The subcontractor is registered under CIS at the standard 20% deduction rate.
If £1,000 of that invoice relates to materials, the CIS deduction only applies to the labour portion.
Example calculation:
Total invoice: £5,000
Materials: £1,000
Labour subject to CIS: £4,000
CIS deduction at 20%: £800
The contractor pays:
£5,000 – £800 = £4,200
The £800 is submitted to HMRC as advance tax on behalf of the subcontractor.
Understanding this breakdown is critical to avoiding over-deduction errors.
What Records Must Contractors Keep Under CIS?
HMRC requires contractors to keep accurate records including:
- Subcontractor verification numbers
- Gross amount paid (excluding VAT)
- Materials cost
- CIS deduction amount
- Payment date
- Monthly CIS return submission confirmation
Records must be kept for at least 3 years.
Digital accounting software simplifies this process significantly.
CIS Monthly Returns Explained
Contractors must submit a CIS return to HMRC every month.
Even if:
- No payments were made
- Or no deductions were required
A nil return must still be filed.
Late returns can result in penalties starting at £100 and increasing over time.
This is one of the most common compliance issues among small trades businesses.
Gross Payment Status Explained
Some subcontractors qualify for Gross Payment Status (GPS).
This means:
- Contractors do not deduct CIS at source.
- The subcontractor handles their own tax obligations.
To qualify, subcontractors must:
- Meet turnover thresholds
- Have a good tax compliance record
- Apply formally to HMRC
GPS can significantly improve subcontractor cash flow.
How Accounting Software Handles CIS
Modern accounting software for trades can:
- Automatically calculate CIS deductions
- Generate monthly CIS reports
- Track subcontractor verification
- Separate materials from labour
- Produce deduction statements
This reduces human error and improves compliance confidence.
For contractors comparing options, see our guide to the best accounting software for trades.
Frequently Asked Questions
Do sole traders need to register for CIS?
Yes, if operating as a contractor in the construction industry.
Are CIS deductions the same as tax?
No. They are advance payments towards tax and National Insurance.
Can you claim CIS deductions back?
Yes. Subcontractors can offset deductions against their annual tax bill.
Does CIS apply to VAT?
CIS does not replace VAT. Both must be managed separately.
Final Thoughts
CIS accounting can appear complex, but with accurate record keeping and the right accounting system, it becomes manageable.
For contractors and subcontractors in 2026, staying compliant means:
- Understanding deduction rules
- Filing monthly returns correctly
- Keeping digital records
- Using reliable accounting tools
CIS compliance is not optional — but it does not need to be overwhelming.