CIS Subcontractors: How to Claim Your Tax Refund Through your Self-Assessment Tax Return
- Pro Acc
- Jun 30
- 3 min read
If you work as a CIS subcontractor anywhere in the UK, the period after 6 April is one of the most important opportunities to improve your financial position.
This marks the start of the new tax year and more importantly, it’s when you can submit your Self-Assessment tax return and claim back any overpaid tax from HMRC.
Any CIS tax refund due is paid directly into your bank account by HMRC once your tax return has been processed.
In our experience, many subcontractors are consistently overpaying tax, often without realising it, simply because their true expenses are not properly accounted for during the year.
Why CIS Subcontractors Often Overpay Tax
Under the Construction Industry Scheme (CIS), contractors deduct tax at source before paying you:
20% for registered subcontractors
30% if you are not registered
These deductions are sent directly to HMRC as advance payments towards your tax bill. However, and this is where many subcontractors lose money: these deductions are calculated without taking your actual business expenses into account.
This means:
You may be taxed on income that is not your true profit
You are often entitled to a tax refund once your real figures are submitted
The only way to correct this position, according to HMRC, is by filing a Self-Assessment tax return.
Why Filing Early Is a Smarter Strategy
A common pattern we see is subcontractors leaving everything until January. While this meets the deadline, it is rarely the most effective approach financially.
Filing your tax return shortly after 6 April offers clear advantages:
Faster Access to Your Tax Refund. HMRC will only process refunds after your return has been submitted. Filing early means receiving your money sooner, sometimes months earlier.
Better Cash Flow Management. For many subcontractors, a tax refund can be substantial. Accessing this earlier can support business costs, personal finances, or reinvestment.
Reduced Risk of Errors. Rushed January filings often lead to missing expenses, incorrect figures or poor record use. Early preparation allows for accuracy and completeness.
Stronger Financial Control. Instead of reacting to deadlines, you are proactively managing your tax position.
What You Need to Prepare Your CIS Tax Return
To submit an accurate and compliant Self-Assessment, HMRC expects you to maintain proper records.
For CIS subcontractors, this typically includes:
Income & CIS Records. CIS deduction statements from each contractor and full income received during the tax year.
Allowable Business Expenses. These reduce your taxable profit and can significantly increase your refund. Common examples include:
Tools and equipment
Travel and mileage to temporary work sites
Protective clothing and safety gear
Materials and consumables
Work-related phone and communication costs
Keeping organised records is not just good practice - it directly affects how much tax you pay or reclaim.
Maximising Your Tax Refund The Right Way
There is a clear distinction between avoiding tax (which is not allowed) and paying only what you legally owe (which is essential).
A properly prepared tax return ensures full compliance with HMRC rules, accurate calculation of your true profit, all allowable expenses are claimed, you receive the maximum refund you are entitled to.
We regularly speak to subcontractors who have missed legitimate expense claims, filed returns too quickly or too late or relied on incomplete or inaccurate figures. The result is simple; they pay more tax than necessary.
Why Acting Early Matters
Delaying your tax return does not reduce your workload - it simply delays your refund. If you’ve had CIS deductions throughout the year, there is a strong likelihood that HMRC may owe you money, but you must take action to claim it. The sooner your return is submitted, the sooner your position is finalised.
How Pro Acc Supports CIS Subcontractors Nationwide
At Pro Acc Chartered Certified Accountants, we work with CIS subcontractors across the UK to ensure their tax affairs are handled correctly and efficiently.
Our approach is straightforward and practical:
We review your CIS statements in detail
Identify all allowable expenses
Prepare and submit your Self Assessment tax return
Ensure full compliance with HMRC
Focus on maximising your tax refund
We do not take a one-size-fits-all approach. Each client’s situation is reviewed properly to ensure nothing is missed.
Take Action – Your Refund Could Be Waiting
If you’ve worked under CIS in the last tax year, now is the time to act.
Filing early puts you in control, improves your cash flow, and ensures you don’t leave money unclaimed.
Get in touch with Pro Acc today
Find out how much tax you could claim back and get your return handled properly from start to finish.
Contact Details
pro acc® Chartered Certified Accountants
T: 01202028585
A: 807 Christchurch Road, Bournemouth, BH7 6AP, UK
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