Can I Reclaim Overpaid CIS Tax from HMRC

At Towerstone Accountants we provide specialist CIS accountancy services for contractors, subcontractors, and construction businesses across the UK. We created this webpage for people working in construction who want clear guidance on CIS, including registration, deductions, refunds, and common compliance tasks, without jargon. Our aim is to help you stay compliant with HMRC, avoid costly errors, and keep your records in good order.

This is one of the most important questions anyone working under CIS can ask, and in my experience it usually comes up after a moment of frustration. Someone looks at their bank statements, adds up what they have earned, then looks at how much has been deducted under CIS and realises the numbers do not feel right. Often they have been paying 20 percent month after month, sometimes 30 percent early on, and they start to worry that the money has simply gone, never to be seen again.

The short answer is yes, you can reclaim overpaid CIS tax from HMRC, but the how, the when, and the amount you can reclaim depends on your circumstances, your business structure, and how well your records are kept. Over the years, running my own accountancy firm and dealing with large numbers of CIS subcontractors, I have reclaimed tens of thousands of pounds for clients who either did not realise they were due a refund or assumed it would happen automatically.

In this article, I am going to explain clearly how CIS tax works, why overpayments happen so often, how and when you can reclaim overpaid CIS tax from HMRC, and what you need to do to make sure you get back everything you are entitled to. I will also cover common mistakes I see, because this is an area where small misunderstandings can delay refunds by months.

How CIS Tax Deductions Actually Work

To understand how to reclaim overpaid CIS tax, you first need to understand what CIS deductions really are.

Under the Construction Industry Scheme, contractors deduct tax from payments made to subcontractors and pay that tax directly to HMRC. For most registered subcontractors, the deduction rate is 20 percent, applied to the labour element of the invoice. If the subcontractor is not registered, the rate increases to 30 percent.

This tax is not a separate or additional tax. It is tax paid on account of your eventual tax bill, similar in principle to PAYE for employees. The problem is that CIS deductions are calculated on gross payments, without taking into account your personal allowance, business expenses, or other reliefs.

Because of this, it is extremely common for CIS deductions to exceed the actual tax that is ultimately due.

Why CIS Overpayments Are So Common

In my experience, CIS overpayments are the norm rather than the exception, especially for sole traders.

There are several reasons for this. CIS deductions are taken at a flat rate and do not consider expenses. Many subcontractors have significant allowable costs such as materials, tools, fuel, vehicle expenses, insurance, and accountancy fees.

CIS also does not take account of the personal allowance, which for many people shelters a large portion of their income from tax altogether.

On top of that, new subcontractors are sometimes deducted at 30 percent before registration is sorted, leading to particularly large overpayments in the early stages.

All of this means that by the time a full tax calculation is done, the tax already paid under CIS is often higher than the true liability.

What Counts as Overpaid CIS Tax

Overpaid CIS tax is simply the amount of CIS deductions that exceeds your final tax liability for the year.

For example, if £15,000 has been deducted under CIS during the tax year, but your final Income Tax and National Insurance bill comes to £9,000, the difference of £6,000 is overpaid tax.

That £6,000 is not lost. It can be reclaimed from HMRC, provided the correct process is followed.

How You Reclaim Overpaid CIS Tax as a Sole Trader

For most sole traders, reclaiming overpaid CIS tax is done through the Self Assessment tax return.

When your tax return is prepared, all your income is declared, all allowable expenses are deducted, and the correct tax liability is calculated. The CIS deductions suffered during the year are then offset against that liability.

If the deductions exceed the tax due, the result is a refund.

This refund is usually paid directly by HMRC once the return has been submitted and processed, assuming there are no outstanding issues.

It is important to understand that HMRC does not automatically calculate this for you unless a tax return is submitted. If you do not file a return, the overpaid tax will not be refunded.

When You Can Reclaim CIS Tax

Timing is one of the most misunderstood parts of CIS refunds.

In most cases, CIS tax is reclaimed after the end of the tax year, once the Self Assessment return has been submitted. The UK tax year runs from 6 April to 5 April, and returns can be filed from 6 April onwards.

This means that even if you have clearly overpaid tax during the year, you usually have to wait until after 5 April to reclaim it through the normal process.

There are some limited situations where in year adjustments can be made, but these are less common and usually require professional involvement.

How Long CIS Refunds Take

Once a tax return is submitted, CIS refunds are usually processed fairly quickly, but timing can vary.

In straightforward cases, refunds can be issued within a few weeks. In more complex cases, or where HMRC carries out checks, it can take longer.

Delays often arise where CIS figures reported by contractors do not match HMRC records, or where deduction statements are missing or incomplete.

This is why keeping accurate CIS statements and checking CIS figures online is so important.

Reclaiming Overpaid CIS Tax for Limited Companies

For limited companies, the process is different.

CIS deductions suffered by a company are not reclaimed through a Self Assessment return. Instead, they are usually offset against PAYE liabilities, such as PAYE tax and National Insurance due on employee and director salaries.

If the company does not have sufficient PAYE liabilities to absorb the CIS deductions, the excess can be reclaimed from HMRC, often through the company’s payroll account.

This is an area where mistakes are common, particularly where CIS deductions are not recorded correctly in the accounts. If the bookkeeping does not reflect the deductions suffered, refunds can be delayed or missed entirely.

What Records You Need to Reclaim CIS Tax

Good records make CIS refunds much smoother.

As a subcontractor, you should keep CIS deduction statements from each contractor. These statements show the gross amount paid and the tax deducted.

You should also keep copies of invoices, payment records, and bank statements.

When reclaiming overpaid CIS tax, the figures on your tax return or payroll records must match what HMRC has on file. If they do not, HMRC may query the refund.

In my experience, missing or inaccurate records are one of the main reasons CIS refunds are delayed.

Checking CIS Deductions With HMRC

Before submitting a tax return, it is good practice to check your CIS deductions online through your HMRC account.

This allows you to see what contractors have reported and compare it to your own records. If there are discrepancies, they can often be resolved before the tax return is filed, reducing the risk of delays.

I regularly see cases where contractors have submitted incorrect returns, and the subcontractor only discovers this when trying to reclaim tax. Catching it earlier saves a lot of time.

What Happens If You Are Deducted at 30 Percent

Being deducted at 30 percent usually happens when a subcontractor is not registered under CIS.

While this higher rate is painful from a cash flow perspective, the tax is still reclaimable. The same principles apply, the deductions are offset against the final tax liability, and any excess can be refunded.

That said, I always advise registering for CIS as early as possible to avoid unnecessary overpayments in the first place.

Common Mistakes That Delay CIS Refunds

There are several issues I see repeatedly that slow down CIS refunds.

CIS figures on the tax return do not match HMRC records
Deduction statements are missing
Income is reported incorrectly
Returns are submitted late
Outstanding tax returns from earlier years are unresolved

HMRC will often hold refunds until all outstanding compliance issues are dealt with.

What If You Stop Working Under CIS

If you stop working under CIS, you can still reclaim overpaid tax in the normal way.

Even if you cease trading altogether, you are still entitled to reclaim any overpaid CIS tax through a final tax return.

This is something people sometimes miss, especially if they leave the construction industry and move into other work.

Can You Reclaim CIS Tax Without an Accountant

Technically, yes, you can reclaim CIS tax without an accountant, but in practice many people struggle to get it right.

CIS involves multiple moving parts, income, expenses, deductions, and HMRC records. Errors can easily creep in, and small mistakes can delay refunds significantly.

In my experience, having professional support often results in faster refunds and fewer queries, especially where amounts are large or records are complex.

How Long You Have to Reclaim CIS Tax

There are time limits for reclaiming overpaid tax.

Generally, you have four years from the end of the tax year to claim a refund. After that, the overpaid tax may be lost.

This is another reason not to delay dealing with CIS issues, especially if you have missed returns from earlier years.

Practical Advice From Experience

Based on years of dealing with CIS refunds, a few principles stand out.

Register for CIS early
Keep every CIS deduction statement
Check CIS figures online regularly
Submit tax returns on time
Deal with discrepancies quickly

These simple habits make a significant difference to how smoothly refunds are processed.

Final Thoughts

So, can you reclaim overpaid CIS tax from HMRC. Yes, absolutely, and in many cases you should.

CIS is designed to collect tax in advance, not to overcharge people permanently. Overpayments are common, particularly for sole traders with significant expenses or personal allowances.

In my experience, the biggest barrier to reclaiming CIS tax is not HMRC policy, but lack of understanding or poor record keeping. Once the process is understood and handled properly, reclaiming overpaid CIS tax becomes a routine part of the annual tax cycle rather than a source of stress.

If you are working under CIS and have never reviewed how much tax has been deducted compared to what you actually owe, it is well worth doing so. There is a good chance HMRC may owe you money, and that is never something to ignore.

You may also find our guidance on how do CIS tax refunds work for subcontractors and how to claim your cis refund from hmrc helpful when dealing with related CIS questions. For a broader overview of CIS rules, compliance, and support, you can visit our cis guidance hub.