Every year, thousands of UK subcontractors overpay tax because nobody explained their CIS tax return properly. Contractors deduct 20% or 30% from your payments before the money reaches you, but that deduction doesn't account for your personal allowance or business expenses. The result is that most subcontractors are owed a refund and simply don't claim it correctly.
What Is a CIS Tax Return?
A CIS tax return is simply your annual Self Assessment tax return, filed with the additional detail needed to account for the tax already deducted from your pay under the Construction Industry Scheme. If you're a subcontractor, your contractor deducts either 20% (if you're registered with HMRC) or 30% (if you're not) from every payment before it reaches you. That money goes straight to HMRC on your behalf. Filing a CIS self-assessment tax return at the end of the tax year is how you tell HMRC exactly how much you earned, how much was already deducted, and how much of that deduction should be refunded to you.
How Does a CIS Tax Return Work?
Throughout the year, your contractor sends you a monthly CIS statement showing your gross pay, the deduction taken, and the net amount you received. Once the tax year ends on 5 April, you gather all these statements together with any allowable business expenses — tools, travel, protective equipment, insurance, and so on.
These figures go into your Self Assessment (SA100) form, along with the CIS deductions already suffered. HMRC then compares what you actually owed in income tax and National Insurance against what was already deducted at source.
In most cases, subcontractors have paid more than they owe, because the deduction doesn't account for your personal allowance or expenses — which is exactly why most CIS refunds land in your favour.
How Long Does a CIS Tax Return Take?
This is the question we get asked most often, and the honest answer depends on a few factors. If your records are organised and your return is filed online with no errors, HMRC typically processes refunds within 2 to 6 weeks. Paper returns take considerably longer, often 8 to 12 weeks, and any missing information, mismatched figures, or late submissions can push this out further still. Filing early — as soon as the tax year closes in April, rather than waiting until the January deadline — is the single biggest thing you can do to speed up your refund.
How to Complete a CIS Tax Return
Here's the process, step by step:
Register for Self Assessment and get your Unique Taxpayer Reference (UTR) if this is your first return.
Gather every CIS statement you received during the tax year from each contractor you worked with.
Cross-check your figures against your invoices and bank statements to make sure nothing's missing.
List your allowable expenses, including materials, tools, fuel, mileage, protective clothing, and public liability insurance.
Complete the SA100 form, entering your income, expenses, and CIS deductions suffered.
Submit before the deadline — 31 October for paper returns, 31 January for online returns — though earlier is always better if you're expecting a refund.
A CIS tax return calculator is worth using before you submit anything. It gives you a rough estimate of your likely refund, so you're not filing blind and can catch obvious errors before HMRC does.
Why Work With CIS Tax Return Accountants
This is where experienced CIS tax return accountants make a genuine difference. It isn't just about filling in a form — it's about making sure every deductible expense is claimed, every CIS statement is reconciled correctly, and your return is filed in a way that doesn't raise red flags with HMRC. A good accountant also knows how to structure your records so next year's return takes a fraction of the time, and can advise on whether applying for gross payment status makes sense for your situation.
Get Your CIS Refund Handled Properly
Chasing paperwork and second-guessing HMRC's rules isn't how you should be spending your evenings after a full day on site. At Malik AccounTax, our ACCA-qualified team handles CIS tax returns for subcontractors and contractors across the UK every day — accurately, quickly, and with every legitimate expense claimed on your behalf. We'll review your CIS statements, calculate exactly what you're owed, and
file your return so your refund lands as fast as possible.
Ready to get your CIS refund sorted?
Call us on 0131 287 7599
Email info@malikaccountax.com
For a free consultation, let's get your money back where it belongs.