CIS Explained for Contractors & Subcontractors
The Construction Industry Scheme, commonly known as CIS, is one of the most important tax schemes for UK construction businesses.
It affects:
- contractors who pay subcontractors
- subcontractors who carry out construction work
- limited companies in construction
- sole traders working in the building trade
- property developers using construction labour
- businesses that spend heavily on construction work
CIS can be confusing because it sits between tax, payroll, bookkeeping and construction invoicing. It is not the same as PAYE, and it is not simply a normal business expense deduction.
Under CIS, contractors deduct money from subcontractor payments and pass it to HMRC. These deductions count as advance payments towards the subcontractor’s tax and National Insurance. Contractors must register for CIS, while subcontractors do not legally have to register, but deductions are taken at a higher rate if they are not registered.
Handled correctly, CIS helps keep tax affairs organised. Handled poorly, it can lead to cashflow problems, penalties, incorrect deductions and messy accounts.
What Is CIS?
CIS is a tax deduction system for the construction industry.
In simple terms:
- the contractor pays the subcontractor
- the contractor checks the subcontractor with HMRC
- HMRC tells the contractor what deduction rate to use
- the contractor deducts CIS from the labour element of the payment
- the contractor pays that deduction to HMRC
- the subcontractor uses the deduction as credit against their tax position
The important point is that CIS deductions are usually advance tax payments, not an additional tax on top of normal tax.
Who Counts as a Contractor?
For CIS purposes, a contractor is generally a business that pays subcontractors for construction work.
You may need to register as a contractor if:
- you pay subcontractors for construction work, or
- your business does not normally carry out construction work but has spent more than £3 million on construction in the 12 months since making the first payment.
This means CIS can affect not only traditional builders, but also some larger property businesses, developers and organisations commissioning substantial construction work.
Who Counts as a Subcontractor?
A subcontractor is a business or individual who carries out construction work for a contractor.
This could include:
- sole trader builders
- limited company subcontractors
- partnerships
- tradespeople working for main contractors
- construction businesses providing labour
A business may be both a contractor and a subcontractor. For example, a construction company may be paid under CIS by a main contractor while also paying its own subcontractors under CIS.
HMRC confirms that a business must register as both contractor and subcontractor where it falls under both categories.
What Type of Work Is Covered by CIS?
CIS covers most construction work to permanent or temporary buildings and structures, as well as civil engineering work such as roads and bridges. HMRC examples of construction work include site preparation, demolition, building work, alterations, repairs, decorating, installing heating, lighting, power, water and ventilation systems, and cleaning the inside of buildings after construction work.
Examples of work commonly within CIS include:
- building work
- plastering
- roofing
- decorating
- repairs and alterations
- electrical installation
- plumbing and heating installation
- demolition
- groundworks
- site preparation
However, not everything connected to construction is automatically within CIS.
HMRC lists exceptions such as architecture and surveying, scaffolding hire with no labour, carpet fitting, making materials used in construction, delivering materials, and site work that is clearly not construction, such as running a canteen or site facilities.
CIS Deduction Rates
There are three main CIS deduction rates:
- 20% for registered subcontractors
- 30% for unregistered subcontractors
- 0% where the subcontractor has gross payment status
HMRC confirms that the deduction rate is provided when the contractor verifies the subcontractor, and the deductions must be paid to HMRC as advance payments towards the subcontractor’s tax and National Insurance.
Practical Example
A registered subcontractor invoices:
- Labour: £2,000
- Materials paid directly by the subcontractor: £500
- VAT: ignored for CIS deduction purposes
The CIS deduction is normally calculated on the labour element after excluding qualifying materials and VAT.
If the subcontractor is registered and the rate is 20%, the contractor deducts CIS from the relevant amount and pays the net balance to the subcontractor.
Materials and CIS: A Common Area of Confusion
CIS is usually deducted from the labour element, not from certain costs such as VAT and qualifying materials.
HMRC guidance says contractors should start with the gross amount of the subcontractor’s invoice, then deduct amounts such as VAT, consumable stores, fuel used except for travelling, plant hire, prefabricated materials and materials the subcontractor paid for directly, before applying the CIS deduction rate to the remaining amount. Contractors may ask subcontractors for evidence, such as receipts, showing they paid for materials directly.
This is one of the most common CIS bookkeeping mistakes.
Practical Scenario
A subcontractor invoices a contractor for £3,000 labour and £1,000 materials.
If the contractor incorrectly deducts CIS from the full £4,000, the subcontractor may suffer too much deduction.
If the contractor incorrectly excludes items that should not be excluded, the contractor may under-deduct CIS.
The invoice breakdown matters.
Contractor Responsibilities Under CIS
If you are a contractor, your responsibilities can include:
- registering for CIS
- verifying subcontractors before paying them
- deducting CIS at the correct rate
- paying CIS deductions to HMRC
- filing monthly CIS returns
- giving deduction statements to subcontractors
- keeping proper CIS records
- checking employment status
Before paying a new subcontractor, contractors must verify them with HMRC. HMRC will confirm whether they are registered for CIS and what deduction rate to use, or whether they can be paid gross. Contractors must also re-verify subcontractors not included on a CIS return in the current or last two tax years.
Why Verifying Subcontractors Matters
Verification is not just admin.
It affects:
- the deduction rate
- whether gross payment status applies
- whether the subcontractor can be paid without CIS deduction
- whether the contractor is applying CIS correctly
To verify a subcontractor, HMRC requires details such as the contractor’s UTR, accounts office reference and employer reference. For the subcontractor, the required details depend on whether they are a sole trader, company or partnership. HMRC also states that the details provided must exactly match the details the subcontractor used to register.
Practical Example
A subcontractor gives the contractor a trading name that does not match HMRC’s records.
HMRC cannot verify them correctly.
The contractor may need to deduct CIS at the higher 30% rate until the issue is resolved.
Monthly CIS Returns
Contractors must tell HMRC each month about payments made to subcontractors through a monthly CIS return. The return can be filed using HMRC’s CIS online service or commercial CIS software. On the return, the contractor must also declare that the subcontractors listed are not employees.
The deadline for monthly CIS returns is the 19th of every month following the last tax month. For example, the return for the tax month 6 May to 5 June must reach HMRC by 19 June.
Nil Returns and Inactivity
If no payments were made to subcontractors, contractors should still file monthly CIS returns unless they have told HMRC they have temporarily stopped using subcontractors. HMRC refers to this as either filing a nil return or making an inactivity request.
CIS Penalties
CIS penalties can become expensive.
HMRC states that late CIS monthly returns can attract penalties starting at £100 for being one day late, £200 if two months late, and further penalties after six and twelve months. Additional penalties can apply for very late returns.
There is also a specific employment status risk. HMRC warns that contractors could receive a penalty of up to £3,000 if they give the wrong employment status for a subcontractor on the monthly return.
This is why contractors should not treat CIS as a simple “deduct 20% and move on” process.
Paying CIS Deductions to HMRC
Contractors must pay CIS deductions to HMRC.
HMRC confirms that if a contractor already has employees, the PAYE scheme will become a PAYE/CIS scheme, and the contractor should usually make one payment each month or quarter covering PAYE tax, National Insurance and CIS deductions. CIS deductions are generally paid to HMRC by the 22nd of the month if paying electronically, or the 19th if paying by post.
Practical Example
A contractor deducts £1,500 CIS from subcontractor payments in the tax month.
That £1,500 is not the contractor’s money.
It must be paid to HMRC by the correct deadline.
Deduction Statements for Subcontractors
Where a contractor makes CIS deductions, they must give the subcontractor a payment and deduction statement within 14 days of the end of each tax month. For example, if the tax month runs from 6 May to 5 June, the statement must be given by 19 June.
These statements are important because subcontractors use them to:
- check deductions
- prepare accounts
- claim tax credits
- support Self Assessment or company payroll claims
- resolve HMRC queries
Subcontractors should keep every CIS deduction statement carefully.
Subcontractor Responsibilities Under CIS
Subcontractors should not assume CIS means tax is fully dealt with.
Even where deductions are made, subcontractors remain responsible for paying the correct tax and National Insurance for their business. HMRC confirms that contractors should provide monthly statements showing payments and deductions, and that these help with accounting.
For sole traders and partners, the full invoice amounts should normally be recorded as income on the Self Assessment tax return, with CIS deductions recorded in the CIS deductions field. HMRC then takes the deductions into account when calculating the final tax and National Insurance position.
For limited company subcontractors, CIS deductions suffered are not claimed through the Corporation Tax return. HMRC says companies should claim these back through the monthly payroll scheme using the FPS and EPS process.
Gross Payment Status
Gross payment status means the subcontractor is paid without CIS deductions.
This can significantly improve cashflow because the subcontractor receives full payment and deals with tax through the normal tax system.
However, not everyone qualifies.
To qualify for gross payment status, HMRC says the business must show it has paid tax and National Insurance on time in the past, does construction work or provides labour for it in the UK, and is run through a bank account. HMRC also applies turnover tests based on the last 12 months, ignoring VAT and materials.
The turnover thresholds include:
- £30,000 for a sole trader
- £30,000 for each partner in a partnership, or at least £100,000 for the whole partnership
- £30,000 for each company director, or at least £100,000 for the company
- for companies controlled by five people or fewer, £30,000 turnover for each of them
Gross payment status is valuable, but it comes with responsibility. If a business receives payments gross, it must be disciplined with tax planning and cashflow because no CIS is being deducted at source.
CIS and Bookkeeping
CIS bookkeeping must be accurate because the same transaction can affect:
- sales
- labour costs
- materials
- VAT
- CIS deducted
- PAYE/CIS liabilities
- Corporation Tax
- Self Assessment
- cashflow
For contractors, the bookkeeping needs to show:
- gross subcontractor invoice amount
- materials excluded from CIS
- CIS deduction made
- net amount paid
- CIS payable to HMRC
For subcontractors, the bookkeeping needs to show:
- full invoice value as income
- CIS deducted by contractor
- net cash received
- CIS credit recoverable or offset
Practical Example: Subcontractor
A subcontractor invoices £2,000 for labour.
The contractor deducts £400 CIS and pays £1,600.
The subcontractor should not record income as only £1,600.
The income is £2,000, and the £400 is recorded as CIS tax deducted.
This distinction matters for accounts, tax returns and cashflow reporting.
CIS and VAT
CIS and VAT are separate systems, but they often interact on construction invoices.
CIS deductions are not normally made from VAT.
HMRC guidance confirms that VAT is excluded before calculating the CIS deduction.
This means VAT-registered contractors and subcontractors need to be careful when preparing and processing invoices.
There may also be domestic reverse charge VAT issues in the construction sector. That is a separate VAT rule and should be reviewed alongside CIS where relevant.
CIS and Employment Status
CIS does not automatically make someone self-employed.
This is a major risk area.
A worker can be paid under CIS, but the underlying working relationship still needs to be considered. HMRC requires contractors to declare on the monthly CIS return that listed subcontractors are not employees, and gives a potential penalty of up to £3,000 for incorrect employment status declarations.
Practical Scenario
A subcontractor:
- works fixed hours
- uses the contractor’s equipment
- cannot send someone else
- is supervised like an employee
- works only for one contractor
Calling the person a subcontractor may not be enough if the facts point towards employment.
This should be reviewed carefully.
CIS Record Keeping
Contractors must keep CIS records showing the gross amount of each subcontractor payment, excluding VAT, and any deductions made. Where deductions are made, contractors must also keep records of material costs invoiced by the subcontractor, excluding VAT. These records must be kept for at least three years after the end of the tax year they relate to, and HMRC can ask to see them at any time.
HMRC states that a contractor can be fined up to £3,000 if they cannot show CIS records when asked.
Good records should include:
- subcontractor invoices
- verification details
- deduction statements
- payment records
- monthly CIS returns
- material evidence
- HMRC payment confirmations
- subcontractor UTR and business details
- contract or work details
Common CIS Mistakes Contractors Make
1. Not Registering as a Contractor
Some businesses pay subcontractors without realising they need to register for CIS.
2. Not Verifying Subcontractors
Failing to verify can lead to incorrect deduction rates.
3. Deducting CIS From the Wrong Amount
CIS should usually be calculated after excluding VAT and qualifying materials, not simply from the full invoice total.
4. Missing Monthly Returns
CIS returns are monthly and have strict deadlines.
5. Forgetting Nil Returns
Where no subcontractor payments are made, a nil return or inactivity request may still be needed.
6. Poor Employment Status Checks
CIS is not a substitute for employment status review.
7. Not Issuing Deduction Statements
Subcontractors need monthly statements to support their own tax records.
8. Weak Record Keeping
If HMRC asks for CIS records, the contractor must be able to provide them.
Common CIS Mistakes Subcontractors Make
1. Not Registering for CIS
Unregistered subcontractors usually suffer deductions at 30%, rather than the standard 20% rate.
2. Giving the Wrong Business Name
HMRC says subcontractors should give contractors the exact same legal business name or trading name used when registering for CIS, as well as their UTR. Incorrect details can affect how much they are paid.
3. Recording Only Net Income
Subcontractors should record gross income and CIS deductions separately.
4. Losing Deduction Statements
Without deduction statements, claiming CIS credits can become more difficult.
5. Assuming CIS Covers All Tax
CIS deductions are advance payments. The final tax position is calculated through Self Assessment or company payroll processes.
6. Limited Companies Claiming CIS Incorrectly
Limited company subcontractors should not claim CIS deductions suffered through the Corporation Tax return. HMRC says they should use the company’s monthly payroll scheme and EPS process.
Practical Scenario: Contractor
A small building company takes on three subcontractors.
Before paying them, the company:
- registers as a CIS contractor
- verifies each subcontractor with HMRC
- receives deduction rates
- checks invoice labour and materials
- deducts CIS correctly
- pays subcontractors net
- gives monthly deduction statements
- files the monthly CIS return by the 19th
- pays deductions to HMRC by the due date
- keeps invoices and material evidence
This is the correct compliance flow.
Practical Scenario: Subcontractor
A self-employed electrician works for a main contractor.
The electrician:
- registers for CIS
- gives the contractor the correct UTR and trading name
- invoices labour and materials separately
- keeps receipts for materials
- receives monthly deduction statements
- records gross income in bookkeeping
- records CIS deducted separately
- includes the figures correctly on the Self Assessment tax return
This avoids common CIS tax return and refund issues.
Frequently Asked Questions
What is CIS?
CIS stands for Construction Industry Scheme. It is a system where contractors deduct tax from payments to subcontractors and pay those deductions to HMRC as advance payments towards the subcontractor’s tax and National Insurance.
Who needs to register as a CIS contractor?
You usually need to register as a contractor if you pay subcontractors for construction work. Some non-construction businesses may also need to register if they spend more than £3 million on construction in the relevant 12-month period.
Do subcontractors have to register for CIS?
Subcontractors do not have to register, but if they are not registered, deductions are usually taken at the higher 30% rate.
What are the CIS deduction rates?
The main CIS rates are 20% for registered subcontractors, 30% for unregistered subcontractors, and 0% where the subcontractor has gross payment status.
Are CIS deductions made from materials?
CIS deductions are not normally made from VAT and qualifying materials paid for directly by the subcontractor. The invoice should clearly separate labour and materials.
When are CIS monthly returns due?
CIS monthly returns are due by the 19th of every month following the last tax month.
When must contractors pay CIS deductions to HMRC?
CIS deductions are generally paid by the 22nd of the month if paying electronically, or the 19th if paying by post.
Can a limited company subcontractor claim CIS through Corporation Tax?
No. HMRC says limited company subcontractors should claim CIS deductions through the company’s monthly payroll scheme using the FPS and EPS process, not through the Corporation Tax return.
How PR Accountants Can Help
At PR Accountants, we help construction businesses stay compliant with CIS and keep their records accurate.
We support contractors and subcontractors with:
- CIS registration
- subcontractor verification
- monthly CIS returns
- CIS deduction calculations
- CIS bookkeeping
- payroll and EPS submissions
- limited company CIS recovery
- Self Assessment tax returns
- Corporation Tax
- VAT and domestic reverse charge support
- management accounts and cashflow reporting
Our aim is to make CIS clear, compliant and manageable, so construction businesses can focus on running their projects without unnecessary tax stress.
Final Thoughts
CIS is more than a deduction on an invoice.
It affects tax, bookkeeping, payroll, cashflow and compliance.
Contractors need to verify subcontractors, deduct correctly, issue statements, file monthly returns and pay HMRC on time. Subcontractors need to register correctly, keep deduction statements, record income properly and claim deductions in the right way.
The businesses that avoid CIS problems are usually the ones with clear systems, accurate bookkeeping and regular compliance checks.
Need Help With CIS Returns, Deductions or Construction Bookkeeping?
CIS mistakes can quickly lead to penalties, incorrect tax deductions and cashflow issues.
PR Accountants provides practical CIS and accounting support for contractors, subcontractors and construction businesses across the UK.
👉 Contact PR Accountants today for clear, reliable CIS and construction accounting support. Contact Us
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