How CIS Subcontractors Can Maximise Their Tax Refund

Paul Edwards
Mar 6
3 min read

If you're a subcontractor working under the Construction Industry Scheme (CIS), you're probably entitled to a tax refund at the end of the tax year. HMRC deducts 20% (or 30% if you're not registered) from your payments throughout the year, often leading to an overpayment. By taking the right steps, you can ensure you claim the maximum tax refund possible.

1. Keep Accurate Records of Your Income and Expenses

One of the most important factors in maximising your tax refund is keeping detailed and accurate records. You should track:

CIS statements from contractors
Invoices and receipts for expenses
Bank statements
Mileage logs
Any other records of business-related spending

Having organised records means you can claim all allowable expenses and ensure you don’t miss out on tax relief.

2. Claim All Allowable Expenses

To maximise your tax refund, you must claim all the expenses you’re entitled to. These may include:

Tools and equipment
Work clothing and protective gear
Travel costs (including mileage for work-related journeys)
Accommodation and subsistence (if working away from home)
Public liability insurance
Training courses and certifications
Accountancy fees

Ensuring you claim all allowable expenses reduces your taxable income and increases your refund.

3. Check Your CIS Deductions

Your contractor should provide you with monthly CIS statements showing the tax deducted from your payments. Check these carefully against your own records to ensure accuracy. Mistakes in CIS deductions can result in an incorrect tax refund calculation, so it’s crucial to address any discrepancies with your contractor or HMRC.

4. Register for the CIS Scheme

If you haven’t already, register as a CIS subcontractor with HMRC. Registered subcontractors have tax deducted at 20%, while unregistered ones have 30% deducted. Reducing your deductions means more money in your pocket throughout the year and a larger refund.

5. Use an Accountant Specialising in CIS Refunds

A specialist accountant can ensure you claim all the tax relief available and handle the tax return process efficiently. They will:

Maximise your expense claims
Check CIS deductions are correct
Submit your tax return accurately and on time
Chase HMRC for a faster refund

Hiring a professional can save you time and help you get the best possible refund.

6. File Your Tax Return Early

The deadline for filing your self-assessment tax return is 31st January, but submitting it early has benefits:

You’ll receive your refund sooner
It helps avoid last-minute stress
You have time to fix any issues or claim missing deductions

Filing early ensures you get your money back as quickly as possible.

7. Keep Up to Date with Tax Rules

HMRC’s tax rules can change, affecting what you can claim and how your refund is calculated. Staying informed about updates to CIS and self-assessment tax regulations ensures you don’t miss out on any opportunities to reduce your tax bill.

Get Help with Your CIS Tax Refund

Maximising your CIS tax refund requires proper planning and accurate record-keeping. If you want to ensure you’re getting the full refund you deserve, working with an experienced accountant can make a significant difference.

At Strength in Numbers, we specialise in helping CIS subcontractors like you claim their maximum tax refunds quickly and efficiently. Contact us today to find out how we can help you get the most out of your tax return!