If you have been working as a construction subcontractor under the Construction Industry Scheme (CIS) and have never filed a Self Assessment return, you could have several years of tax refunds sitting unclaimed with HMRC. Many subcontractors do not realise that the overpayment from years ago is still recoverable, within limits.
This guide explains the rules on how far back you can claim, what you need, and what happens if you leave it too long.
Quick Answer
You can claim a CIS tax refund for up to four tax years. Once a year passes the four-year window, the refund is lost permanently. In the 2025/26 tax year, you can still claim back to 2021/22. After 5 April 2026, the 2021/22 year closes and cannot be reclaimed.
The Four-Year Rule
HMRC allows individuals to claim overpaid tax for up to four years after the end of the relevant tax year. For CIS subcontractors, this means:
| Tax year | Claim deadline |
|---|---|
| 2021/22 | 5 April 2026 |
| 2022/23 | 5 April 2027 |
| 2023/24 | 5 April 2028 |
| 2024/25 | 5 April 2029 |
The deadline is absolute. HMRC has no discretion to extend it, regardless of the circumstances.
Why Do Subcontractors Overpay?
Your contractor deducts 20% (or 30% if you are not CIS registered) from your gross payment before you are paid. This is an advance tax payment. But your actual tax liability is almost always lower, because:
- You have a personal allowance (£12,570) that means the first portion of your income is tax-free
- You can deduct legitimate business expenses from your income before tax is calculated
- You may not have worked a full year
- You may have gaps between contracts where you earned nothing
The result is that most subcontractors who file a return receive a refund. The deduction system is deliberately set to collect in advance rather than under-collect.
What Records Do I Need?
To file a return and claim your refund, you will need:
CIS deduction statements. Your contractor must provide a statement for each payment showing gross pay, CIS deductions made, and any materials costs excluded. These should be provided monthly. If you do not have them, ask your contractors to reissue them. A tax specialist can also access deduction information HMRC holds on your behalf.
Business expense records. Receipts or records for tools, equipment, protective clothing, fuel and vehicle costs, materials, insurance, and any other business-related costs. Even estimates supported by bank statements can help where receipts are missing, though proper records are always preferable.
UTR number. Your Unique Taxpayer Reference. If you do not know yours, HMRC can provide it.
National Insurance number. Needed for registration and filing.
What If I Have Not Registered for Self Assessment?
If you have never registered for Self Assessment, you will need to do so before filing. Registration takes a few days for HMRC to process. A tax specialist can register you and handle the entire process on your behalf, including chasing HMRC for any delays.
If you are registering late, note that you should have registered by 5 October following the first year you needed to file. HMRC may issue a late registration penalty in some cases, though this is often waived for first-time registrations where there is a genuine reason for the delay.
Filing Multiple Years at Once
If you have two, three, or four years of unfiled returns, you can file all of them. Each year is treated separately and has its own refund calculation. In many cases the total refund across multiple years is substantial.
The process involves:
- Registering for Self Assessment (if not already done)
- Gathering deduction statements and expense records for each year
- Preparing and filing each year’s return in sequence, oldest first
- HMRC processing each return and issuing refunds
Multi-year claims are a core part of what Kent Tax Specialists does for CIS subcontractors. The paperwork involved is straightforward for an experienced specialist, even if the volume appears daunting.
How Long Does the Refund Take?
Once a return is filed and processed by HMRC, refunds are typically issued within 4 to 6 weeks. HMRC issues them by bank transfer (if you have provided bank details) or by cheque. If there is a delay beyond 8 weeks, your tax agent can chase HMRC directly.
FAQs
I worked under CIS for three years and never filed. Is it too late? As long as the years in question are within the four-year window, it is not too late. File now. Every day you delay could cost you a year’s refund if the oldest year is approaching its deadline.
My contractor went out of business and I cannot get my deduction statements. What do I do? HMRC holds records of CIS deductions submitted by contractors. A tax specialist can access this information on your behalf using your UTR and authority to act. Even without the original statements, it is often possible to prepare an accurate return.
Can I claim a CIS refund for a year where I also had other income? Yes. Your Self Assessment return covers all income for the year, including CIS income, employment income, and any other sources. The refund is calculated on your overall tax position.
My CIS deduction was 30% because I was not registered. Can I still claim? Absolutely. In fact, unregistered subcontractors who were deducted at 30% almost always receive larger refunds, because the deduction rate was significantly higher than their actual tax liability.
Will filing late returns cause problems with HMRC beyond missing years? Filing late can attract late filing penalties, typically starting at £100 per year. However, where a refund is due, HMRC will offset the penalty against the refund, meaning you still receive a net payment. A tax specialist will calculate whether you owe any penalties and what you will net after offset.
Claim Every Year You Are Owed
Our principal tax adviser is an ACCA and ATT qualified tax specialist and HMRC Registered Agent with over 25 years of personal tax experience handling CIS refund claims across Kent. Do not leave previous years unclaimed. Kent Tax Specialists handles multi-year CIS claims for subcontractors across Gravesend, Dartford, Maidstone, Medway, Chatham and the wider Kent area. Get in touch today and we will tell you exactly what you are owed.
Also see: CIS Refunds in Gravesend | CIS Refunds in Medway | CIS Refunds in Maidstone
