How To Claim A Corporation Tax Refund - A Step By Step Process
Updated: Aug 12
How to Claim a Corporation Tax Refund: A Step-by-Step Process in the UK
A company that has overpaid Corporation Tax is entitled to a refund from HMRC, and in most cases the refund process is straightforward. If your CT600 shows a lower liability than the amount already paid, HMRC usually repays the difference automatically after processing the return. No separate claim form is required for a simple overpayment. The rate of repayment interest HMRC pays on overpaid Corporation Tax is currently 2.75%.
The complexity increases depending on why the refund arises, which determines whether it flows through the standard CT600 filing, requires an amended return, or involves specific supplementary pages and additional steps.
Why Might a Company Be Owed a Corporation Tax Refund?
Before working through the process, it is worth being clear about the different situations that generate a CT refund, because they each follow a slightly different route.
Simple Overpayment Against Assessed Tax
Where a company paid an estimated Corporation Tax liability, perhaps by setting up a payment to meet the nine-month-and-one-day due date, and the CT600 subsequently shows that the actual liability was lower, the excess paid is a straightforward overpayment. This is the most common scenario for small to medium-sized companies. HMRC processes the refund automatically once the return is filed.
Trading Loss Carry-Back
A trading loss arising in one accounting period can be carried back and set against the profits of the preceding 12 months. If Corporation Tax was already paid for that earlier period, the carry-back reduces the prior period's profits and generates a refund of the tax attributable to the relieved amount. A company with a year end of 31 March 2026 making a £80,000 trading loss in that period can carry the loss back to the year ended 31 March 2025, where it had taxable profits. If the tax was already paid on those profits, the carry-back produces a repayment.
The claim is made in the CT600 for the loss-making period. The standard carry-back window is 12 months. Terminal loss relief, applicable when a company ceases trading, allows losses from the final 12 months of trade to be carried back up to three years.
HMRC does not generally accept a claim for repayment of Corporation Tax that depends on events in a subsequent accounting period that has not ended at the time of the claim. So a company cannot claim a loss carry-back until the accounting period in which the loss arises has actually ended. This is a practical timing point that sometimes causes frustration where a company knows it will make a loss but has not yet reached its year end.
Amended Return: Correcting an Error After Filing
Where a company filed its CT600 and later discovers an error, such as an overclaimed income figure, an understated allowable expense, a capital allowance claim that was missed, or an R&D credit that was not included, the route to the refund is an amended return. You have four years from the end of the accounting period to amend your CT600 and claim a refund for overpaid Corporation Tax. After four years, the right to claim is lost.
R&D Tax Credits
Where a company claims relief under the merged RDEC scheme or ERIS, and the credit exceeds the Corporation Tax liability for the period, the excess can become a payable credit. This is a slightly different process from a standard overpayment refund and involves specific supplementary pages on the return and, for first-time claimants, the pre-notification requirement. This is covered separately below.
What this Widget is About: Welcome to the Corporation Tax Refund visual explainer, designed by Pro Tax Accountant to demystify the process of claiming your overpaid tax from HMRC. This interactive widget breaks down the various refund scenarios, whether you are dealing with a simple overpayment, a trading loss carry-back, an amended return, or R&D tax credits. It clearly outlines the step-by-step actions you need to take, highlighting crucial deadlines, statutory requirements, and expected processing times. To use the tool, simply click through the different tabs and expand the sections to reveal tailored guidance relevant to your specific business situation. By navigating this easy-to-understand guide, UK taxpayers can confidently ensure they meet all HMRC requirements and secure their rightful refunds without unnecessary delays.
Step 1: Confirm the Refund Entitlement and the Basis for It
Before filing or amending anything, confirm that the refund claim is correct and that the basis for it is sound. For a simple overpayment, this is a reconciliation of payments made against the CT600 liability. For a loss carry-back, it requires verifying the loss figure in the current period, checking that the prior period profits are correctly stated, and calculating the tax saving at the appropriate rate for that prior period.
For the 2026/27 tax year, the Corporation Tax rates remain 25% for profits above £250,000 and 19% for profits at or below £50,000, with marginal relief applying to profits between £50,000 and £250,000 at an effective marginal rate of 26.5%. Where a loss carry-back relates to a prior period that attracted a different rate, the refund is calculated at the rate applicable in that prior period, not the current year rate.
Step 2: Prepare or Amend the CT600
HMRC's own free CT600 filing service closed in March 2026. All Corporation Tax returns for periods ending on or after that date must now be filed using commercial software. HMRC has a list of approved software providers on its website.
For a Standard Filing with an Overpayment
Where the company has not yet filed for the accounting period in question, the CT600 is prepared as normal. The tax computation shows the correct liability. The company enters its bank details, sort code and account number, in the designated section of the return. This is the critical step that ensures the refund arrives by bank transfer rather than by cheque to the registered office. HMRC cannot process a repayment until your CT600 is filed.
In the CT600, make sure you have ticked box 95 to request repayment of any overpaid tax. If box 95 is left unticked, HMRC may hold the credit on your account rather than issuing the refund. That credit will then be set against the next Corporation Tax liability rather than being returned, which is not the same as a refund arriving in the company's bank account.
For an Amended Return
Where the CT600 has already been filed and the refund arises from a discovered error or missed claim, the return must be amended within the four-year window. In the company's commercial tax software, open the relevant accounting period, select the option to amend or revise the return, make the corrections to the accounts, tax computations, and the CT600 form as appropriate, and resubmit.
Where bank details were not entered on the original return, they should be included on the amendment. If the company's bank details have changed since the original return was submitted, HMRC must be notified via the amended return, a signed letter from the company or its agent on headed paper, or an email from a known and trusted address.
Step 3: The Loss Carry-Back Claim , Specific Points
Carrying a loss back to recover tax paid in a prior period requires care in the CT600 completion. The loss arising in the current period must first be set against any profits of the same period before it can be carried back. Only the unused portion is available for carry-back.
The claim is included on the CT600 for the loss-making period. HMRC then needs to recalculate the earlier period's liability, which means that even though the carry-back claim appears on the current year return, HMRC will check the prior year position before processing the repayment.
One practical note: where you are waiting for a repayment from a carry-back claim already made, do not send in an amended return. Resubmitting may increase the time for HMRC to review and process the claim. HMRC has confirmed this guidance on its website. The instinct to do something when a refund is slow to arrive can actually make things slower.
Step 4: The R&D Payable Credit Route
For companies claiming R&D relief under the merged RDEC scheme or ERIS, the process of obtaining a payable credit requires several steps beyond the standard CT600:
Pre-notification: For first-time claimants or companies that have not claimed in the previous three years, a claim notification form must have been submitted within six months of the accounting period end before the CT600 can be filed with the R&D claim. An R&D claim in the CT600 without a prior notification, where one was required, is invalid.
Additional Information Form: All R&D claims from accounting periods commencing on or after 8 August 2023 require a separately submitted Additional Information Form to be in place before the CT600 is filed. This form contains the technical and financial detail of the R&D projects.
CT600L: The supplementary page CT600L is used for RDEC and ERIS claims. It walks through the statutory steps for applying the credit: first against the Corporation Tax liability of the period, then (if any credit remains) against other HMRC liabilities, with any remaining amount becoming a payable credit.
Bank details must be included in the CT600 to receive the payable credit. For large repayments (£1 million or above), the payment is made by CHAPS, and bank details, including the bank name and address, account name, number, and sort code, must be specifically confirmed.
The R&D credit route has more moving parts than a standard overpayment refund, and the timing can extend over several months if HMRC selects the claim for a repayment verification review. HMRC has statutory powers to investigate R&D claims before paying, and large payable credits in particular may be subject to a check before the cash is released.
Step 5: Register Bank Details Through the Business Tax Account
Where bank details were not included in the CT600, or where the company wants to update them separately, this can be done through the company's Business Tax Account on HMRC's online portal.
After a CT600 is accepted, HMRC takes a few days to fully process the return and update the Business Tax Account. During this window, the repayment section may not be visible. This is normal: check back after two to three working days. Look for the option labelled "Add or amend repayment bank details." Enter the sort code and account number. HMRC will use these details to transfer the credit balance.
Repayments of below £1 million are sent by the Faster Payment System. Repayments of £1 million or more are made by CHAPS. Cheques, known as payable orders, are issued only where no bank details have been provided, and they are considerably slower.
Step 6: Timescales and Chasing the Refund
The typical processing time for a standard CT overpayment refund, where the bank details are registered and the return is clean, is five to ten working days after the return is processed. For claims involving loss carry-backs or R&D credits, the timeline is longer. Allow at least six weeks from the point of submission. Complex claims or those selected for verification review can take twelve weeks or more.
HMRC's peak period for Corporation Tax returns is from December to April, which corresponds to the volume of returns due following the most common accounting year ends. Claims submitted during this period may experience longer processing times.
If six weeks have passed with no communication or payment, the appropriate next step is to check the Business Tax Account for any HMRC correspondence and then, if necessary, to contact HMRC's Corporation Tax helpline on 0300 200 3410, Monday to Friday, 8am to 6pm. The helpline is less busy between 8:30am and 11am. For agents contacting HMRC on behalf of a client, the agent helpline should be used.
Where HMRC takes longer than expected to process the refund, repayment interest accrues. HMRC's current Corporation Tax repayment interest rate is 2.75%. Interest runs from the later of the date the tax was paid or the normal due date for that period. Repayment interest is taxable: the company must include it as income in the next CT600. The refund itself is not taxable, only the interest element.
Not Sure How to Claim Your Corporation Tax Refund?
The general rule is one thing. What it means for you is another. Tell us your circumstances and one of our UK tax specialists will give you a straight answer on your own position. Free, no obligation.
UK Corporation Tax Refund Claim Process
Process Step | Key Action Required | Standard Timescale | Important HMRC Forms/References |
1. Assess Eligibility & Overpayment | Identify overpaid tax via trading losses, Construction Industry Scheme (CIS) offsets, R&D credits, or repaid Director's Loans (s455). | Before filing deadline (typically within 2 years for losses, 4 years for errors) | Section 37 CTA 2010; Section 455 CTA 2010; CTM |
2. Prepare Evidence & Notifications | Collate bank details, CIS statements, and iXBRL computations. Submit mandatory R&D Pre-notifications or Additional Information Forms (AIF) if applicable. | Within 6 months after the end of the period of account for R&D notifications | Form CT600L; Additional Information Form (AIF); Claim Notification Form |
3. Submit Claim via Tax Return | File or amend Form CT600. Tick Box 40 for repayment, Box 45 for loss carry-back, or include CIS offsets in Box 515. Provide bank details in boxes 920-940. | 12 months after accounting period ends for standard filing | Form CT600 (Boxes 40, 45, 515, 920-940); Form CT600A (for s455) |
4. Alternative/Manual Submission | Submit a standalone letter for "Fast-Track" loss claims or use Form L2P for s455 tax reclaims if the 2-year amendment window has closed. | 9 months and 1 day after the period of repayment (for s455) | Form L2P; Section 37 CTA 2010; HMRC BX9 1AX |
5. HMRC Processing & Refund | HMRC verifies the claim, offsets the balance against existing tax debts (VAT/PAYE), and issues the remaining total via BACS or cheque. | 4 to 8 weeks (Standard); 6 to 12 weeks (Loss carry-back); 28 days (R&D target) | HMRC Business Tax Account; Repayment Interest (2.75%) |
Do not resubmit returns or duplicate claim forms while a refund is pending. HMRC's guidance explicitly states that resubmitting may increase processing time.
What this Widget is About: This interactive visual explainer walks UK limited-company directors and their accountants through every common route to reclaiming an overpaid Corporation Tax refund from HMRC. It covers simple overpayments, trading-loss carry-backs, amended returns, R&D payable credits and the separate CIS offset process, while highlighting the current 2.75 % repayment-interest rate, the four-year overpayment-relief window and the fact that HMRC’s free CT600 filing service closed in March 2026. Simply click the coloured reason cards or the numbered step tabs to expand the exact actions, box numbers and timing tips you need; each panel opens cleanly without leaving the page. Bank-detail instructions, typical processing times and the official helpline number are all included so you can move from confirmation to cash receipt with confidence. Created by Pro Tax Accountant, the widget is fully responsive and ready to drop straight into a Wix HTML box, giving taxpayers a clear, up-to-date checklist in one place.
The CIS Offset Route: Different From a Standard CT Refund
For limited company subcontractors under the Construction Industry Scheme, CIS deductions suffered can be offset against the company's monthly PAYE, NIC, and CIS liabilities. Where the deductions exceed those liabilities over the year, the net balance can be claimed as a repayment from HMRC.
This is a distinct process from the standard Corporation Tax refund route. All relevant PAYE, CIS, and Corporation Tax returns must have been submitted before a CIS repayment can be processed. The claim can be made online through HMRC's Business Tax Account or, for older claims, in writing to HMRC.
Key Takeaways
If your CT600 shows a lower liability than the amount already paid, HMRC usually repays the difference automatically after processing the return, provided bank details are registered and box 40 is ticked.
The current HMRC Corporation Tax repayment interest rate is 2.75%. Interest is taxable and must be declared as income in the next CT600.
You have four years from the end of the accounting period to amend a CT600 and claim a refund. After that deadline, the right to claim is permanently lost.
Trading losses can be carried back 12 months (three years for terminal losses). The claim is made on the CT600 for the loss-making period after the period has actually ended.
For R&D payable credits, pre-notification (for first-time claimants) and the Additional Information Form must both be in place before the CT600 is filed. CT600L is the supplementary page for RDEC and ERIS claims.
After filing, register or confirm bank details through the Business Tax Account. Repayments under £1 million are sent via Faster Payment. Payable orders by post are significantly slower.
Do not resubmit a claim or file an additional amended return while a repayment is being processed. HMRC has confirmed that duplicate submissions extend processing times rather than accelerating them.
How a Tax Accountant Can Help You Claim a Corporation Tax Refund
In the complex landscape of UK corporate taxation, navigating the intricacies of claiming a corporation tax refund can be daunting for businesses of all sizes. This is where the expertise of a tax accountant becomes invaluable. A tax accountant plays a crucial role in ensuring that your business not only complies with tax laws but also maximizes its potential for receiving a corporation tax refund. Here’s how a tax accountant can assist in this process:
Expert Guidance on Tax Laws and Regulations
Tax laws in the UK are subject to frequent changes and updates. A tax accountant stays abreast of these changes, providing expert advice on how new tax laws and regulations can affect your corporation tax refund claim. They can interpret complex tax legislation and translate it into actionable advice, ensuring that your business remains compliant while optimizing tax reliefs and deductions.
Identifying Eligible Tax Reliefs and Deductions
One of the key ways a tax accountant can assist is by identifying the various tax reliefs and deductions for which your business is eligible. This may include research and development (R&D) tax credits, capital allowances, or relief on charitable donations. By thoroughly understanding your business operations, a tax accountant can pinpoint specific areas where you can reduce your taxable profit, thereby increasing the potential for a corporation tax refund.
Accurate Preparation and Submission of Tax Returns
Filing accurate and timely tax returns is essential for claiming a corporation tax refund. A tax accountant ensures that your Company Tax Return (CT600) is correctly filled out and submitted before the deadline. They can handle the intricate details of your financial statements, ensuring that all relevant income and expenditures are accurately reported. This minimizes the risk of errors and delays in processing your refund claim.
Managing Compliance Checks and Inquiries from HMRC
HMRC may conduct compliance checks or raise inquiries regarding your tax return. A tax accountant can manage these interactions on your behalf, providing clear and concise responses to HMRC's questions. Their expertise can be particularly valuable if your claim is complex or involves substantial amounts of money, helping to navigate the compliance check process smoothly and efficiently.
Streamlining the Claim Process
A tax accountant can streamline the entire process of claiming a corporation tax refund. They can gather and organize the necessary documentation, calculate the refund amount accurately, and communicate with HMRC on your behalf. This not only saves you time but also ensures that your claim is processed as quickly and smoothly as possible.
Advising on Tax-efficient Strategies
Beyond claiming a refund, a tax accountant can advise on tax-efficient strategies for your business. This includes structuring your business operations, investments, and expenses in a way that minimizes tax liabilities and maximizes eligibility for future refunds. They can provide strategic advice on financial planning, helping your business to grow while maintaining tax efficiency.
Offering Peace of Mind
Perhaps one of the most significant benefits of hiring a tax accountant is the peace of mind it offers. Knowing that an expert is handling your corporation tax refund claim can relieve the stress associated with tax filings. It allows you to focus on running your business, confident in the knowledge that your tax affairs are in good hands.
The role of a tax accountant in claiming a corporation tax refund in the UK is multifaceted and extends beyond mere tax filing. From providing expert guidance on tax laws, identifying eligible reliefs and deductions, to managing communications with HMRC, a tax accountant is an invaluable asset to any business seeking to optimize its tax position. By leveraging their expertise, businesses can navigate the complexities of the tax system more effectively, ensuring compliance and maximizing their financial health.
FAQs
Q1: Can a company’s Corporation Tax refund be reduced because HMRC owes money on another tax account?
A1: Well, it is worth noting that HMRC can use a Corporation Tax repayment to clear other debts first, such as PAYE or VAT. It can also set it against the company’s next Corporation Tax bill or a late filing penalty unless a repayment limit is entered on the next Company Tax Return. So, if the refund looks smaller than expected, the money has not necessarily vanished; it may simply have been netted off against another balance on the company’s record.
Q2: Can a company claim a Corporation Tax refund through the Company Tax Return itself?
A2: Yes. HMRC says the Company Tax Return is the route used to tell it that a repayment is due and how the repayment should be paid. If the company includes bank details on the return, HMRC can pay the money straight into that account, and it says that helps the repayment move through faster. In practice, this is the cleanest route for most owner-managed businesses because it keeps the claim tied to the accounting period that created it.
Q3: What happens if the company spots the mistake after the normal amendment window has closed?
A3: If the usual amendment window has passed, the company may still be able to claim overpayment relief. HMRC’s current guidance says the time limit is generally four years from the end of the relevant accounting period, so the dates matter more than the amount involved. I have seen small companies lose track of this after a simple capital allowance error, which is why it is worth checking the deadline before assuming the tax is lost for good.
Q4: Can trading losses create a Corporation Tax refund instead of being carried forward?
A4: Yes, but only if the loss is claimed properly in the Company Tax Return. HMRC says a trading-loss claim forms part of the return, and the CT600 boxes have to match the way the loss is being used. For a company that has had a quiet quarter, that can mean turning the loss into a repayment by carrying it back against an earlier profitable period rather than leaving it to sit unused. A useful practical point is that the loss claim normally needs to be made within two years of the end of the loss-making period.
Q5: Can companies in the same group use another company’s losses to recover Corporation Tax?
A5: Yes, where there is a qualifying group relationship, certain losses can be surrendered against another group member’s profits. That is often the more efficient route when one company has overpaid tax and another has made the loss. The common mistake is assuming the repayment must stay with the loss-making company; in a group, the best relief route can sit with whichever company has the profit to absorb it.
Q6: Do bank details on the Company Tax Return really make a difference?
A6: Yes, they do. HMRC says that if the account number and sort code are included on the Company Tax Return, the repayment is automatically sent to the bank account and is usually processed more quickly. It sounds like a small admin detail, but in real life it can be the difference between a smooth repayment and a pointless chase later on.
Q7: Is HMRC repayment interest taxable?
A7: Yes. HMRC says it may pay interest where Corporation Tax was paid early or overpaid, and that interest is taxable, so it should be included in the Company Tax Return. The current repayment interest rate shown on HMRC’s guidance is 2.75%, which is why even a modest overpayment can produce a small but real extra amount for the company.
Q8: Can a company still get a refund when it is closing and the loss arises in the final period?
A8: It can, and this is one of the more valuable edge cases. HMRC’s terminal loss relief rules can allow losses from the final 12 months of trading to be carried back against profits in the final year and the three prior years, starting with the latest year first. I have seen directors overlook this because they assume closure means the claim is finished, when in reality the final period can be the most valuable one to review carefully.
Q9: What should a company do if HMRC is already querying the repayment?
A9: Do not send duplicate claims. HMRC specifically warns that if a repayment claim is already in progress, resubmitting an amended return or sending the same claim again in writing can slow the process down. The safer move is to use the contact details on HMRC’s letter, or HMRC’s general Corporation Tax contact route, and respond only to what is actually being asked for.
Q10: How can a company tell whether a refund letter or text from HMRC is genuine?
A10: Well, it is worth being cautious here. HMRC says it will not ask for personal or payment details through a suspicious refund text or email, and it warns people not to click links in unexpected rebate messages. A sensible habit in any business is to verify the message through HMRC’s genuine-contact guidance before anyone acts on it, especially where bank details or a repayment instruction is involved.
About the Author:
Adil Akhtar, ACMA, CGMA, FCMA, (membership ID is 990250923) serves as CEO and Chief Accountant at Pro Tax Accountant, bringing over 18 years of expertise in tackling intricate tax issues. As a respected tax blog writer, Adil has spent more than eighteen years delivering clear, practical advice to UK taxpayers. He also leads Advantax Accountants, (registered with Companies House), combining technical expertise with a passion for simplifying complex financial concepts, establishing himself as a trusted voice in tax education.
Email: adilacma@icloud.com
Disclaimer:
The content provided in our articles is for general informational purposes only and should not be considered professional advice. Pro Tax Accountant strives to ensure the accuracy and timeliness of the information but makes no guarantees, express or implied, regarding its completeness, reliability, suitability, or availability. Any reliance on this information is at your own risk. Note that some data presented in charts or graphs may not be 100% accurate.
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