CIS Tax Refund Estimator 2026/27

Q: How much CIS tax can I claim back?

The amount you can claim back depends on your total taxable income, allowable expenses, and how much CIS tax was deducted. If your actual tax liability is less than the CIS deductions taken, HMRC will refund the difference. Most CIS subcontractors receive a refund because deductions are taken at 20% or 30% of gross pay, which often exceeds the actual tax due.

Q: What is the difference between 20% and 30% CIS deductions?

Registered CIS subcontractors have tax deducted at 20% of gross payments. Unregistered subcontractors (those not registered with HMRC under CIS) have tax deducted at 30%. Registering with HMRC as a subcontractor reduces your deduction rate from 30% to 20%, meaning you keep more of your money throughout the year.

Q: When will I get my CIS tax refund?

After you submit your Self Assessment tax return, HMRC typically processes CIS refunds within 4-8 weeks. To get your refund as quickly as possible, submit your return online and ensure your bank details are up to date with HMRC.

Last Updated9 May 2026 · HMRC 2026/27 rates

Estimate your CIS tax rebate for the 2026/27 tax year. Works for both 20% (registered) and 30% (unregistered) CIS deduction rates. Include your expenses for a more accurate refund estimate.

🏗️ Your CIS Income

Total CIS Gross Payments (before deductions)

Total amount paid to you by contractors before any CIS deductions.

CIS Deduction Rate

Registered CIS subcontractors pay 20%. Unregistered subcontractors pay 30%.

CIS Tax Already Deducted

Total amount already deducted from your payments. We'll auto-calculate this if left at 0.

Other Taxable Income (optional)

Any other employment or self-employment income.

🛠️ Business Expenses

Add your allowable expenses to reduce your taxable profit and increase your refund.

Total Expenses

💰 Your CIS Tax Estimate

CIS Net Profit

Total Taxable Income

Income Tax + NICs Due

CIS Already Deducted

Your estimated CIS tax position

How CIS Tax Refunds Work

Under the Construction Industry Scheme (CIS), contractors deduct tax from payments to subcontractors and pass it directly to HMRC. These deductions act as advance payments toward your final tax bill.

Registered subcontractors — 20% deducted from gross payments
Unregistered subcontractors — 30% deducted from gross payments
At tax year end, you file a Self Assessment tax return
HMRC calculates your actual tax liability based on profit (income minus expenses)
If CIS deductions exceed your tax liability, you receive a refund
If your tax liability exceeds CIS deductions, you owe additional tax

Most CIS subcontractors receive a refund because the flat 20% or 30% deduction rate is often higher than the actual effective tax rate after expenses and the Personal Allowance are applied.

Frequently Asked Questions

How much CIS tax can I claim back?

The amount depends on your total taxable income, allowable expenses, and how much CIS tax was deducted. If your actual tax liability (Income Tax + Class 2/4 NICs) is less than the CIS deductions already taken, HMRC will refund the difference. Most CIS subcontractors who claim all allowable expenses receive a significant refund. Use our calculator above to get your personal estimate.

What is the difference between 20% and 30% CIS deductions?

Registered CIS subcontractors have tax deducted at 20% of gross payments. Unregistered subcontractors have tax deducted at 30%. Registering with HMRC as a CIS subcontractor immediately reduces your deduction rate from 30% to 20%, meaning you keep significantly more of your money throughout the year. Register for CIS on Gov.uk.

What expenses can I claim as a CIS subcontractor?

Common allowable expenses include: tools and equipment, protective clothing (PPE), vehicle costs (mileage at 45p/mile for first 10,000 miles, then 25p), fuel for work travel, accommodation when working away from home, phone costs used for work, trade subscriptions, public liability insurance, accountancy fees, and training courses directly related to your work. Keep all receipts and records. You cannot claim for travel between home and your regular workplace.

When will I get my CIS tax refund?

After submitting your Self Assessment tax return online, HMRC typically processes CIS refunds within 4-8 weeks. Submitting online is faster than paper returns. Ensure your bank details are up to date with HMRC to receive your refund by direct bank transfer. You can check your refund status through your HMRC Personal Tax Account.

Do I need to register for Self Assessment as a CIS subcontractor?

Yes. All CIS subcontractors must register for Self Assessment, even if you're also employed elsewhere. You need to file a tax return by 31 January following the end of the tax year (which runs 6 April to 5 April). This is how you claim your CIS refund. If you don't register and file, you won't receive any refund you're entitled to, and HMRC may issue penalties.

How do I register for CIS?

You can register as a CIS subcontractor online through HMRC's CIS registration page. You'll need your UTR (Unique Taxpayer Reference), National Insurance number, and business details. Once registered, contractors will deduct 20% instead of 30% from your payments. Registration is free and can be done at any time.

Sources & Methodology

All calculations are verified against official HMRC thresholds and rates for the 2026/27 tax year. Class 2 NIC is £3.45/week (£179.40/year) for profits above £6,725. Class 4 NIC is 6% on profits between £12,570 and £50,270, and 2% above. Calculations are for guidance only — consult a qualified accountant for personalised advice.

What You Should Do Next

Register for CIS — If you're on 30% deductions, register immediately to drop to 20%. Register on Gov.uk.
Keep detailed expense records — Every receipt increases your refund. Use a dedicated business bank account and apps like Receipt Bank or Expensify.
File your Self Assessment early — Don't wait until January. Filing early means getting your refund sooner. Use HMRC's free online service or an accountant.
Consider the VAT Flat Rate Scheme — If your turnover exceeds £85,000, the CIS flat rate VAT scheme can simplify your VAT returns. Try our VAT Calculator.