If you work in construction under the Construction Industry Scheme (CIS), you've probably had 20% deducted from every payment before it even reaches your bank account. Most CIS subcontractors overpay tax, and you can claim that money back. The average CIS tax refund is between £2,000 and £3,000 per year.
This guide walks you through the process step by step.
What Is a CIS Tax Refund?
A CIS tax refund is money you get back from HMRC when you've paid more tax than you actually owe. Under the Construction Industry Scheme, your contractor deducts 20% from your pay (or 30% if you're not registered) and sends it straight to HMRC. But that flat 20% doesn't take into account your personal allowance, your expenses, or how much you actually earned that year.
Once you file your Self Assessment tax return and declare your income, expenses, and CIS deductions, HMRC works out what you really owe. If they've taken too much — and they usually have — the difference comes back to you.
Key point: CIS deductions are not a final tax. They're advance payments. Your actual tax bill is almost always lower.
Who Can Claim a CIS Tax Refund?
You can claim a CIS refund if you tick all of these boxes:
- You're a self-employed subcontractor registered under CIS
- Your contractor has deducted CIS tax from your payments
- Your total tax liability for the year is less than the amount deducted
- You've filed (or are filing) a Self Assessment tax return
- Your tax affairs are up to date with HMRC
If you've had any gaps between jobs, paid for your own tools, travelled to different sites, or earned less than the personal allowance (£12,570), there's a very strong chance you're owed money.
How to Claim Your CIS Tax Refund: 7 Steps
Step 1: Register for Self Assessment
If you haven't already, you need to register with HMRC for Self Assessment. You'll get a Unique Taxpayer Reference (UTR) — a 10-digit number you'll need for everything.
Register online at GOV.UK. It can take up to 10 working days to get your UTR by post.
Important: If you started self-employed work during the tax year, you must register by 5 October following the end of that tax year.
Step 2: Gather Your CIS Statements
Your contractor should give you a monthly payment and deduction statement (PDS). This shows how much you were paid, how much was deducted, and the materials cost.
Collect all your CIS statements for the tax year (6 April to 5 April). If you've lost any, ask your contractor for replacements. If they've stopped trading, contact HMRC's CIS helpline.
Step 3: Add Up Your Allowable Expenses
This is where most people leave money on the table. You can claim back the cost of anything you spent "wholly and exclusively" for your construction work. For a full breakdown, see our guide to CIS expenses you can claim. Common expenses include:
- Travel: Mileage to temporary work sites (not your regular site if you're there for more than 24 months)
- Tools and equipment: Drills, saws, hand tools, ladders, power tools
- Protective clothing: Steel-toe boots, hard hats, hi-vis vests, gloves, safety glasses
- Public liability insurance
- Phone bills (business portion)
- Accountancy fees
- Training and courses (directly related to your current trade)
- Materials you bought yourself
- Subsistence: Meals when working away from home
Keep receipts and records for at least 6 years. HMRC can check your return at any time.
Step 4: Log In to HMRC Online
Go to GOV.UK and sign in with your Government Gateway ID. If you don't have one, you'll need to create it — you'll need your UTR and National Insurance number.
Step 5: Complete Your Self Assessment Tax Return
Fill in the self-employment section of your tax return. You'll need to declare:
- Your total CIS income (gross, before deductions)
- Your total CIS deductions (from your statements)
- Your allowable business expenses
- Any other income (PAYE jobs, savings, etc.)
The tax return calculates your actual tax liability. If your CIS deductions are higher than what you owe, the difference is your refund.
Step 6: Submit Your Return
File your return online by 31 January following the end of the tax year. (Paper returns must be in by 31 October.) Check our full guide to CIS tax return deadlines so you don't miss any key dates.
Filing earlier means you'll get your refund earlier. There's no benefit to waiting.
Step 7: Receive Your Refund
Once HMRC processes your return, they'll pay your refund directly to your bank account. Online returns are typically processed within 2-6 weeks. Paper returns take longer.
Can I Claim My CIS Refund Early?
Yes, in some cases. If you've stopped self-employed work during the current tax year and your tax affairs are up to date, you can apply for an in-year refund using HMRC form CIS40. This means you don't have to wait until the end of the tax year.
How Much Could You Get Back?
The amount depends on your income, expenses, and how much CIS tax was deducted. See our worked examples for how much CIS refund you could get by trade. Or use our free CIS tax refund calculator to get an estimate in under 60 seconds.
→ Calculate your CIS tax refund now
Frequently Asked Questions
How long does a CIS tax refund take?
After you submit your Self Assessment online, HMRC typically processes refunds within 2 to 6 weeks. Paper returns take up to 12 weeks. If it's been longer than 40 working days, contact HMRC.
Can I claim CIS tax refund for previous years?
Yes. You can file tax returns for up to 4 previous tax years. If you haven't claimed for 2021/22, 2022/23, or 2023/24, you could be owed thousands in unclaimed refunds.
Do I need an accountant to claim my CIS refund?
No. You can file your Self Assessment yourself through HMRC's online system. However, a good accountant or tax app can help you maximise your expenses and avoid mistakes.
What if my contractor hasn't given me CIS statements?
Contact your contractor and ask for replacement statements. If they've stopped trading or won't cooperate, write to HMRC's CIS helpline with as much detail as you can provide.
What's the CIS tax deduction rate?
If you're registered with CIS, the standard deduction rate is 20%. If you're not registered, it's 30%. If you have gross payment status, nothing is deducted.
Ready to find out how much you're owed? Use our free CIS tax refund calculator — it takes less than a minute.
Related Guides
- CIS Expenses You Can Claim — The complete list of allowable expenses for construction subcontractors
- How Much CIS Refund Will I Get? — Worked examples showing typical refund amounts by trade
- CIS Tax Return Deadlines — Every filing and payment date you need to know for 2025/26
Last updated: August 2025. This guide uses 2024/25 and 2025/26 HMRC tax rates and thresholds. MyCISRefund.com is not a tax adviser — for personal tax advice, consult a qualified professional.