CIS accountant in West London
CIS deducted from your pay is not the same as your final tax bill.
SV&Co helps construction subcontractors and contractors across Southall, Hayes, Ealing, Wembley and wider West London with CIS registration, Self Assessment, refunds, records and ongoing CIS compliance.
20% deducted does not mean you are due a 20% refund.
Your final position depends on taxable profit, allowable expenses, tax and National Insurance, and the CIS already deducted by contractors.
How CIS deductions work
CIS is an advance payment system.
Under CIS, contractors deduct money from payments to subcontractors and send it to HMRC. HMRC treats those deductions as advance payments towards the subcontractor’s tax and National Insurance.
Standard deduction
A registered subcontractor will normally have 20% deducted from the relevant CIS payment amount.
The deduction is not normally calculated on VAT or on qualifying direct material costs paid by the subcontractor.
Higher deduction
The higher rate is normally 30% where the subcontractor is not registered, cannot be verified, or gives incorrect business details.
If you believe 30% is being deducted incorrectly, registration and verification should be checked quickly.
Gross payment status
With gross payment status, the contractor pays without CIS deduction. HMRC currently applies business, turnover and compliance tests.
- Sole trader turnover test, currently at least £30,000 excluding VAT and materials.
- Partnership/company tests can use £30,000 per relevant person or £100,000 for the whole business, subject to HMRC’s detailed rules.
Payment statements matter
If CIS is deducted, the contractor must give a payment and deduction statement. HMRC requires it within 14 days after the end of the relevant tax month.
Keep these statements. They help support the deductions claimed through your tax return or company payroll records.
How a CIS refund arises
The contractor deducts tax before knowing your final profit.
Your contractors see the payment they make to you. They do not calculate your annual allowable expenses, Personal Allowance or full Self Assessment position.
Contractor pays you
CIS may be withheld from the relevant payment.
You calculate annual profit
Business income less allowable expenses, subject to tax rules.
Self Assessment calculates tax
Income Tax, Class 4 NIC and other Self Assessment items are considered.
CIS already paid is credited
If the CIS credit exceeds the final liability, a repayment may arise. If it is lower, further tax may be due.
A CIS refund is not guaranteed.
Someone with high taxable profit, other income, student loans, payments on account or low allowable expenses can have a smaller refund or still owe tax.
What we normally need
Give us the evidence behind the CIS claim.
CIS income and deductions
- Payment and deduction statements from contractors.
- Invoices or earnings records.
- Business bank statements.
- Details of any 30% deductions or missing CIS statements.
- Previous tax return where useful.
Business expenses
- Receipts and invoices.
- Vehicle or mileage records where relevant.
- Tools and equipment purchases.
- Insurance, phone and other trade costs.
- Any unusual or large transactions needing review.
Limited-company subcontractors
A company’s CIS deduction is not reclaimed through the Corporation Tax return.
HMRC requires limited-company subcontractors to claim CIS deductions through the company’s payroll scheme using Employer Payment Summary reporting. The credit can offset PAYE and National Insurance liabilities, with excess amounts carried through the tax year and a repayment route available after year end where the HMRC conditions are met.
During the tax year
- Run payroll and send FPS as normal.
- Report CIS suffered through the EPS.
- The credit offsets PAYE/NIC liabilities.
- Unused credit can carry forward within the tax year.
After the year end
- Make sure PAYE, CIS and Corporation Tax returns are up to date.
- Check HMRC has the contractor deduction information.
- Claim repayment of qualifying excess CIS credit where appropriate.
- Do not put the CIS suffered claim through the Corporation Tax return.
Interactive CIS tools
Understand the deduction, then estimate the possible tax position.
Official source: GOV.UK / HMRC
Last checked: 16 August 2026
Live site will use SV&Co Official Data Hub
CIS deduction calculator
Simple illustration for an invoice excluding VAT.
Possible sole-trader CIS repayment illustration
This shows why the refund depends on profit and final tax, not the CIS rate alone.
CIS FAQs
Quick answers before you contact us.
Why is my contractor deducting 20%?
Registered subcontractors are normally paid under the standard CIS deduction rate of 20%. The contractor sends the deduction to HMRC as an advance payment towards your eventual tax and National Insurance.
Why am I being deducted at 30%?
The higher rate normally applies where you are not CIS registered, cannot be verified by the contractor, or incorrect business details prevent a successful match.
Does 20% CIS mean I will receive a refund?
No. Your final refund depends on your taxable business profit, expenses, personal tax position and the CIS already deducted.
How does a sole trader claim CIS deductions?
A sole-trader subcontractor normally claims credit for CIS deductions through the Self Assessment return.
How does a limited company claim CIS suffered?
A limited-company subcontractor normally reports CIS suffered through its payroll using the EPS process. HMRC says not to claim it through the Corporation Tax return.
What if my CIS statements do not match HMRC?
HMRC can compare the amount claimed with contractor returns. Keep payment and deduction statements and investigate missing or incorrect contractor reporting before relying on a refund figure.
Reviewed by
Sandip Vadher, PhD FCCA
Founder of SV&Co Accountancy. Fellow Chartered Certified Accountant with more than 20 years of finance and accountancy experience.
Need help with CIS?
Send us your CIS statements and tell us what you need checked.
We can review the deductions, accounts, expenses and tax position before the claim is submitted.
Useful starting information
Tell us whether you are a sole trader or limited company, the tax year, approximate CIS deductions suffered, and whether your records are complete.
How a CIS refund accountant can help
First, a CIS refund accountant checks the deductions shown on your contractor statements against the income in your records. Next, we review allowable costs and confirm that your tax return includes complete and consistent figures. Then, we explain the calculation so you can understand the refund or tax due. As a result, you can submit an accurate return with evidence ready for HMRC. However, you should keep every deduction statement, invoice and expense receipt. Finally, contact SV&Co if you need help reviewing your CIS records or preparing the return.
In addition, SV&Co checks whether every CIS deduction appears in the records. For example, we compare monthly statements with invoices and bank receipts. Therefore, missing deductions can be identified before the return is filed. Also, we review costs that relate directly to the construction work. Because evidence matters, we explain which receipts and records you should retain. Meanwhile, you remain informed about the expected refund or liability. If HMRC asks questions, organised records support a quicker response. Afterwards, we provide the figures needed for your files. Consequently, the return reflects the available evidence. In summary, careful preparation reduces avoidable delays.