CIS Refund Estimator
CIS deductions are taken from your labour payments before any expenses or personal allowance are accounted for. Most registered subcontractors overpay and are owed a refund. Enter your figures to get an estimate.
CIS Refund Estimator
CIS deductions are taken from your labour payments before any expenses or personal allowance are accounted for. Most registered subcontractors overpay and are owed a refund. Enter your figures to get an estimate.
The total amount on your CIS invoices before any deductions. Include both labour and materials you invoice for.
Materials you personally purchase and include on your invoices. These are excluded from the CIS deduction base.
Mileage (55p per mile from April 2026), tools, PPE, van running costs, phone, work clothing. Do not include personal expenses.
Include any non-CIS income that forms part of your total taxable income for the year.
This is an estimate based on 2026/27 rates (PA £12,570, tapering above £100,000; basic 20%, higher 40%, additional 45%; Class 4 NI 6%/2%). It assumes no other credits or adjustments. A specialist CIS accountant will identify all allowable deductions and file your Self Assessment correctly.
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How CIS tax refunds work
CIS deductions are taken from your labour payments at source, before any account is made for your personal allowance, business expenses or materials costs. A registered subcontractor on a 20% deduction rate may pay 20% on every labour pound received, even if their actual income tax liability for the year is far lower.
The refund is calculated at the end of the tax year through a Self Assessment return. Your total CIS deductions are offset against your actual tax and National Insurance liability, and HMRC refunds the difference. Third-party reported averages put the annual refund for a registered CIS subcontractor at around £2,000 (illustrative, not guaranteed).
This calculator applies the 2026/27 rates: personal allowance of £12,570, income tax at 20% (basic) and 40% (higher rate), and Class 4 NI at 6% up to £50,270 and 2% above. It does not include Class 2 NI, which is £0 for profits above the £7,105 small profits threshold.
Frequently asked questions
What is the average CIS refund?
Third-party reported averages put the annual refund for a registered CIS subcontractor at around £2,000 (illustrative, not guaranteed). The actual figure depends on your total gross income, materials costs, allowable expenses and whether you have other income sources. Subcontractors with high materials costs or significant business expenses typically see higher refunds.
How long does a CIS refund take?
HMRC does not publish a processing time for Self Assessment repayments. It asks you to use its 'Check when you can expect a reply from HMRC' tool, which it updates weekly, and a repayment picked up by its security checks can take up to a further 12 weeks on top of the date that tool gives. What you control is the start of the clock: you cannot file until the tax year ends on 5 April, so filing in April or May rather than the following January is the one lever that reliably brings the money forward.
Can a limited company claim a CIS refund?
Yes, but the mechanism is different. A CIS-registered limited company offsets CIS deductions suffered against its monthly PAYE liability via the Employer Payment Summary (EPS), recovering the money in real time rather than waiting for year-end Self Assessment. This is significantly faster.
Can I claim back CIS deductions for previous years?
Yes. You can claim back overpaid CIS deductions going back up to four tax years from the current year. Each year requires a separate Self Assessment return or amendment. You will need your CIS payment and deduction statements for each year.
What records do I need to claim my CIS refund?
You need your CIS payment and deduction statements (issued by each contractor who deducted CIS from your payments), receipts for all business expenses including materials, mileage records, and details of any other income. Contractors are legally required to issue statements within 14 days of each payment.
Do I need an accountant to claim my CIS refund?
There is no legal requirement to use an accountant, but a specialist CIS accountant will identify all allowable expenses, ensure the deduction base has been applied correctly on your statements, and maximise your refund. Errors in self-filed returns, such as using net income instead of gross or missing expense categories, frequently result in lower refunds.
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