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    CIS Tax Calculator UK - Free CIS Deduction Calculator 2026/27

    CIS Payment Details

    Enter your CIS payment details to calculate deductions

    CIS Tax Calculator UK

    Our CIS tax calculator helps UK construction workers, subcontractors, and self-employed tradespeople calculate CIS deductions for 2026/27. Enter your gross payment, materials cost, and CIS status to see the deduction amount, net payment, and annual projection.

    The Construction Industry Scheme (CIS) requires contractors to deduct money from subcontractors' labour payments and pass it to HMRC as advance payment towards tax. This CIS deduction calculator applies the standard rates: 30% for unregistered subcontractors, 20% for registered subcontractors, and 0% for gross payment status.

    You can also use the results as a starting point for CIS refund, rebate, and tax return planning. If your total CIS deductions are higher than your final Income Tax and National Insurance bill after allowable expenses, you may be able to claim back the overpayment through Self Assessment.

    How to Calculate CIS Deductions

    CIS deductions are calculated on the labour part of a construction payment. Materials are normally excluded, so the basic calculation is: gross payment minus materials, then apply the CIS rate for your status.

    Payment Structure

    When you calculate CIS deductions, you need to understand the components of your payment:

    Gross Payment:The total amount the contractor agrees to pay you (including materials and labour)
    Materials Cost:The cost of materials that become part of the permanent structure, such as cement, bricks, timber, or tiles
    Labour Payment:Gross payment minus materials. This is the amount the CIS rate is applied to

    Deduction Rates by Status

    The calculator applies the rate based on your subcontractor status:

    Unregistered Subcontractor (30% CIS Rate)

    Example: Dave is an unregistered plasterer. He invoices £3,000 (£500 materials, £2,500 labour).

    Gross payment:£3,000
    Less materials:-£500
    Labour subject to CIS:£2,500
    CIS deduction (30%):-£750
    Net payment received:£2,250

    Note: Registering for CIS usually reduces the deduction rate from 30% to 20%.

    Registered Subcontractor (20% CIS Rate)

    Example: Sarah is a registered electrician. Same £3,000 invoice (£500 materials, £2,500 labour).

    Gross payment:£3,000
    Less materials:-£500
    Labour subject to CIS:£2,500
    CIS deduction (20%):-£500
    Net payment received:£2,500

    Savings: Registration saves Sarah £250 per £3,000 invoice compared to being unregistered. Our CIS calculator shows these savings clearly.

    Gross Payment Status (0% CIS Rate)

    Example: BuildPro Ltd has gross payment status. Same £3,000 invoice structure.

    Gross payment:£3,000
    Materials (tracked but not deducted):£500
    CIS deduction (0%):£0
    Net payment received:£3,000

    Note: Gross payment status requires £30k+ annual construction turnover and strong HMRC compliance history.

    Annual CIS Deductions

    Our CIS tax calculator projects your annual CIS deductions based on payment frequency. This helps you:

    • Plan cash flow throughout the year
    • Estimate total CIS deductions for Self Assessment
    • Calculate whether you'll owe more tax or get a CIS refund
    • Budget for expenses and living costs

    Annual CIS Projection Example:

    Mark earns £2,000/week (registered subcontractor, 20% CIS rate):

    Weekly gross:£2,000
    Weekly CIS deduction (20%):£400
    Annual gross (52 weeks):£104,000
    Annual CIS deductions:£20,800
    Annual net received:£83,200

    CIS Tax Refund & Rebate Calculator

    Many construction workers pay tax in advance through CIS deductions during the year. Because contractors deduct CIS at 20% or 30% from labour payments, some subcontractors are due a CIS tax refund when they file their Self Assessment tax return.

    Use this CIS rebate calculator as a deduction checker first: work out how much has been deducted from each payment, then compare your total CIS deductions with your actual tax liability after allowable expenses. Your monthly CIS payment and deduction statements are the key records for this calculation.

    When You'll Get a CIS Refund

    You're likely to get a CIS refund if:

    • Your CIS deductions exceed your actual tax and NI bill for the year
    • You have significant allowable business expenses (tools, van, insurance, etc.)
    • You earned less than the higher rate threshold but had 20%/30% CIS deducted
    • You only worked part of the tax year
    • You can claim capital allowances for equipment purchases

    How to Calculate Your CIS Tax Refund

    1. Add up all CIS deductions shown on your statements for the tax year.
    2. Work out your taxable profit after allowable business expenses.
    3. Calculate your Income Tax and National Insurance liability on that profit.
    4. Subtract your final liability from your CIS deductions. If the deductions are higher, the difference may be your CIS refund.
    5. Claim the overpayment through your Self Assessment tax return.

    CIS Tax Return Deadlines

    To claim a CIS rebate for the 2026/27 tax year, the online Self Assessment deadline is 31 January 2028. Filing earlier can help you confirm whether you are due a refund or still have tax to pay.

    CIS Net to Gross Calculation

    A CIS net-to-gross calculation works backwards from the amount you received to estimate the labour amount before deduction. This is useful if you know your net payment but want to understand the gross labour value shown on the contractor's statement.

    Registered subcontractor

    If 20% CIS was deducted, divide the net labour payment by 0.8.

    Example: £1,600 net labour ÷ 0.8 = £2,000 gross labour.

    Unregistered subcontractor

    If 30% CIS was deducted, divide the net labour payment by 0.7.

    Example: £1,400 net labour ÷ 0.7 = £2,000 gross labour.

    Materials should be handled separately because they are normally not subject to the CIS deduction.

    CIS Refund Example

    Scenario: Tom is a registered carpenter. He wants to compare CIS already deducted with the tax and National Insurance due after business expenses.

    Income & CIS Deductions:

    Gross income (all jobs):£45,000
    CIS deducted (20%):£9,000
    Money already paid to HMRC:£9,000

    Allowable Expenses:

    Van expenses:£3,500
    Tools & equipment:£1,800
    Insurance & licenses:£900
    Mobile & office:£800
    Total expenses:£7,000

    Actual Tax Calculation:

    Gross income:£45,000
    Less expenses:-£7,000
    Taxable profit:£38,000
    Less personal allowance:-£12,570
    Taxable income:£25,430
    (All at 20% basic rate)
    Income tax due (20%):£5,086
    Class 2 NI (£3.45/week):£179
    Class 4 NI (on £25,430):£1,635
    Total tax & NI owed:£6,900
    Less CIS already paid:-£9,000
    CIS REFUND DUE:£2,100

    Result: Tom's CIS deductions (£9,000) are higher than his estimated tax and NI liability (£6,900), so the example shows a potential £2,100 repayment through Self Assessment.

    How to Claim Your CIS Refund

    1. 1Keep all CIS deduction statements from contractors (CIS vouchers showing deductions taken)
    2. 2Record all business expenses with receipts (van, tools, materials purchased, insurance, etc.)
    3. 3File Self Assessment by 31 January including all income, expenses, and CIS deductions
    4. 4HMRC calculates any refund after your return is processed and pays it to your nominated account or offsets it against tax you owe

    CIS Deduction Rate Examples

    Unregistered (30%)

    Gross Payment:£2,000
    Materials:£300
    Labour Payment:£1,700
    CIS Deduction (30%):£510
    Net Payment:£1,490

    Registered (20%)

    Gross Payment:£2,000
    Materials:£300
    Labour Payment:£1,700
    CIS Deduction (20%):£340
    Net Payment:£1,660

    Gross Payment (0%)

    Gross Payment:£2,000
    Materials:£300
    Labour Payment:£1,700
    CIS Deduction (0%):£0
    Net Payment:£2,000

    How to Register for CIS

    Benefits of Registration

    • ✓Reduce CIS deduction rate from 30% to 20%
    • ✓Improve cash flow with lower deductions
    • ✓Eligibility for gross payment status in future
    • ✓Professional recognition in the industry
    • ✓Easier tracking of tax payments

    Registration Requirements

    1. 1Obtain a Unique Taxpayer Reference (UTR) from HMRC
    2. 2Register online at gov.uk or call HMRC CIS helpline
    3. 3Provide business details and contact information
    4. 4Wait for confirmation and start using lower deduction rate

    CIS Rates and Rules 2026/27

    Deduction Rates

    • Unregistered subcontractors: 30%
    • Registered subcontractors: 20%
    • Gross payment status: 0%
    • Materials cost: Exempt from CIS deductions

    Key Deadlines

    • Monthly returns due: 19th of following month
    • CIS deduction statements: End of tax year
    • Self Assessment filing: 31 January
    • Registration deadline: Within 3 months of first payment

    CIS Tax Calculator FAQs

    What is the CIS deduction rate?+
    The CIS deduction rate depends on your HMRC registration status. Registered subcontractors usually have 20% deducted from labour payments. Unregistered subcontractors usually have 30% deducted. Subcontractors with gross payment status have 0% deducted under CIS and settle their tax through Self Assessment.
    How do I calculate CIS deductions?+
    To calculate CIS deductions, subtract allowable materials from your gross payment, then apply the CIS rate to the labour amount. The rate is normally 20% for registered subcontractors, 30% for unregistered subcontractors, or 0% for gross payment status. This CIS deduction calculator does that calculation automatically.
    How do I calculate my CIS tax refund?+
    To estimate a CIS tax refund, add up all CIS deductions shown on your payment and deduction statements for the tax year. Then compare those deductions with your actual Income Tax and National Insurance liability after allowable business expenses. If the deductions are higher than your final tax bill, the difference may be repayable through Self Assessment.
    What is the difference between CIS and PAYE?+
    PAYE is used for employees, where an employer deducts tax and National Insurance through payroll. CIS is used for self-employed subcontractors in construction. Under CIS, contractors deduct tax from labour payments, but the subcontractor remains self-employed and still files a Self Assessment tax return.
    Who qualifies for gross payment status under CIS?+
    Gross payment status is available to subcontractors who meet HMRC tests for business activity, turnover, and tax compliance. For many sole traders this includes at least £30,000 of construction turnover and a good record of meeting tax obligations. If approved, contractors pay you without CIS deductions and you handle the tax through Self Assessment.
    How do I claim back CIS overpayments?+
    CIS overpayments are normally claimed through your annual Self Assessment tax return. Enter your income, allowable expenses, and CIS deductions from your deduction statements. HMRC then compares the CIS already deducted with your final tax bill and refunds any overpayment or offsets it against tax you owe.
    What qualifies as materials cost under CIS?+
    Materials costs can usually be excluded from CIS deductions if they are genuine materials used for the construction work, such as bricks, timber, tiles, cement, or similar items. Labour, travel, fuel, plant hire, and general business overheads should not simply be treated as materials for CIS deduction purposes.
    Do I need to submit monthly CIS returns?+
    Contractors must submit monthly CIS returns to HMRC by the 19th of each month, showing payments made to subcontractors and deductions taken. Subcontractors do not submit monthly CIS returns, but they should keep their CIS payment and deduction statements for their Self Assessment tax return.

    Related Tax Calculators

    CIS deductions usually need to be checked against self-employed tax, VAT and broader construction income. use the self-employed tax calculator for the annual tax position, use the VAT calculator for VAT on invoices and use the side hustle tax calculator for smaller secondary jobs.

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