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CIS tax rebate calculator 2026/27

Estimate whether the CIS deducted from your pay this year is more than your real Income Tax and National Insurance bill, and how big your refund could be.

  • Sole traders and partners
  • 2026/27 GOV.UK rates
  • Nothing is sent anywhere
Illustration: a builder's invoice split into labour, materials and the CIS deduction £

Your year

Everything you invoiced in the tax year, including materials you charged for, excluding VAT.
Materials, tools, PPE, van costs, insurance, accountant's fees and other costs of the business.
The total from your monthly payment and deduction statements.
Where do you live?

Your estimate

Estimated CIS refund

£1,428.20

CIS deducted vs. tax you actually owe

CIS deducted

Income Tax + Class 4 NI due

Full working
Profit (income minus expenses)£34,000.00
Personal Allowance£12,570.00
Taxable profit£21,430.00
Income Tax£4,286.00
Class 4 National Insurance£1,285.80
Total tax and NI due£5,571.80
CIS already deducted£7,000.00
Refund (or tax to pay if negative)£1,428.20

Assumes CIS self-employment is your only income, no student loan, pension or Gift Aid adjustments and no payments on account. Your actual refund is worked out by HMRC from your return.

How the estimate is worked out

  1. Profit = CIS income minus allowable expenses.
  2. Personal Allowance of £12,570, reduced by £1 for every £2 of income over £100,000.
  3. Income Tax: 20% basic, 40% higher, 45% additional (England, Wales and Northern Ireland); Scotland uses 19%, 20%, 21%, 42%, 45% and 48% bands.
  4. Class 4 National Insurance: 6% on profits from £12,570 to £50,270, and 2% above.
  5. Refund = CIS deducted minus (Income Tax + Class 4 NI).

Sources: GOV.UK Income Tax rates · Scottish Income Tax · Self-employed NI rates · Claim back deductions

Worked example

A self-employed bricklayer in England invoices £40,000 in 2026/27, has £6,000 of expenses and had £7,000 deducted under CIS.

Profit£34,000.00
Income Tax (20% of £21,430)£4,286.00
Class 4 NI (6% of £21,430)£1,285.80
Total due£5,571.80
Estimated refund£1,428.20

CIS rebate questions

How is a CIS tax rebate worked out?

Your real bill is Income Tax and Class 4 National Insurance on your profit (income minus allowable expenses). The CIS your contractors deducted is set against that bill. If more was deducted than you owe, HMRC refunds the difference after you file your Self Assessment return.

When can I claim my CIS refund for 2026/27?

The 2026/27 tax year ends on 5 April 2027. You can file your Self Assessment return after that; if you still owe tax, it must be paid by 31 January 2028.

Do limited companies claim CIS refunds the same way?

No. A limited company sets CIS deductions against its PAYE bill using the Employer Payment Summary (EPS) during the year, and claims a refund of anything left over after the tax year ends. It must not use the Corporation Tax return for this. See our guide to claiming back CIS.

What do I need to claim?

The monthly payment and deduction statements from each contractor. Keep them: HMRC may ask for evidence of your deductions. If you lose one, ask the contractor for a replacement.

Does the rebate calculator include Class 2 National Insurance?

No. For 2026/27, GOV.UK says that if your profits are £7,105 or more, Class 2 is treated as paid, so you do not have to pay it.

Last updated: Checked against GOV.UK by the UK CIS Calc teamTax year 2026/27 (6 April 2026 to 5 April 2027)

Need the deduction on a single invoice instead? Use the CIS deduction calculator. Read how to claim back CIS deductions.

Not affiliated with HMRC. Estimates only, not tax advice.