The company tax return filing process is about to undergo a significant change as HMRC prepares to shut down its free online service from next year.
HM Revenue & Customs (HMRC) has officially announced the permanent closure of its free online filing service for company tax returns and annual accounts.
The service will cease operations on 31 March 2026, marking the end of a system that has been in place since 2011 when online filing for corporation tax was first introduced.
This announcement confirms the closure of a long-standing facility that thousands of UK businesses have relied upon to submit their CT600 company tax return to HMRC and accounts to companies house at the same time.
HMRC’s joint online filing service has been a crucial resource for small businesses and their accountants, specifically those managing multiple clients.
Companies can still use HMRC’s web service to submit annual accounts to companies house.
Stopping the free company tax return service affects all businesses that currently use the online facility, particularly small and unrepresented companies with straightforward tax affairs for whom the system was originally designed.
Affected companies must now prepare for this change by reviewing their current company tax return and companies house filing methods.
Importantly, this closure will impact various groups including small unrepresented businesses, dormant companies, charities, and accounting professionals.
The decision stems from several factors including outdated technology, new legal requirements, and enhanced security standards that the current system apparently cannot support.
This article examines why HMRC is making this change, which businesses will be affected, what steps organisations should take before the 2026 deadline, and how to smoothly transition to corporation tax software solutions.
What companies must do before the 2026 deadline
Companies using HMRC’s joint online filing service must take several critical actions prior to the March 2026 shutdown.
With the system’s decommissioning, some companies face some essential tasks to ensure a smooth transition to alternative filing methods.
Making this transition early rather than waiting until the deadline allows businesses to familiarise themselves with new systems and avoid potential filing issues.
During the transition period up until the March 2026 deadline companies can continue using the service to file and amend their company tax returns with HMRC, and submit their accounts to companies house.
If companies need to make amendments to previously submitted returns after the service closes, they will have several options: using commercial software (though information will need to be re-entered), submitting paper returns to HMRC, or enlisting an agent to handle the process.
Download and save past company tax return submissions
Firstly, businesses must download and save at least three years of previously filed returns before 31 March 2026.
After this date, companies will permanently lose access to their historical submissions through the HMRC service. To save these critical records:
- Log in to HMRC and navigate to ‘track your submissions’.
- Select the relevant filing period and choose either ‘HMRC’ or ‘Companies House’ link.
- On the filing summary page, click ‘save your return in HTML’.
- Save the file securely on your computer or network.
These records may prove vital in case of compliance checks, when hiring an accountant, or for resolving future queries with HMRC or companies house.
Review current company tax return filing methods
Secondly, companies should begin evaluating their current tax return process immediately rather than waiting until the deadline approaches.
Planning early allows businesses to:
- Choose appropriate third party company tax return software compatible with both HMRC and companies house requirements. Many software providers offer testing phases that enable businesses to validate their submissions without penalties.
- Consider using an accountant or tax advisor.
- Import or enter historical data.
- Run validation checks to identify potential errors.
- Test the submission process without deadline pressure.
- Familiarise themselves with new interfaces and workflows.
- Train staff on how to use the new company tax software with the potential option of dedicated training sessions provided by software vendors.
Check eligibility for paper filing exemptions
Finally a select group may qualify for exemptions from mandatory online filing. Paper returns remain an option for companies with a reasonable excuse.
Specific entities potentially eligible for corporation tax filing exemptions include:
- Charities.
- Community amateur sports clubs.
- Flat management companies.
- Dormant companies.
These exemptions require prior approval from HMRC and organisations must continue filing annual accounts with companies house either way.
Regardless of exemption status, businesses can start using commercial software at any time without notifying HMRC or companies house.
Choosing HMRC-approved company tax software providers
Selecting appropriate company tax return software can begin with reviewing HMRC’s published list of approved suppliers for corporation tax.
HMRC maintains a comprehensive online directory of approved corporation tax software suppliers that can generate company tax returns.
These solutions vary in functionality, with some offering:
- Complete end-to-end processing versus bridging software.
- Different levels of support for various tax schedules.
- Varying capabilities for attachment handling and amendments.
- Free options for businesses with simple tax affairs.
Businesses should verify whether potential software supports all of their required income sources and tax schedules.
Companies with specific needs like handling complex tax situations should double check that their chosen solution accommodates their particular requirements and not assume everything is covered.
If you don’t have an accountant or tax agent it might be worth contacting one to review how they might be able to work with you.
They will already be working with corporation tax software providers which could make the process easier for your business and future proof your corporation tax return submission process.
Which companies and users will be affected
The closure of HMRC’s free company tax return filing platform will impact various categories of businesses across the UK, with three distinct groups facing significant adjustments to their tax submission processes.
Small and unrepresented businesses
Primarily, the HMRC online service was originally designed to support small, unrepresented businesses with simple tax affairs.
These are typically limited companies without accountants or tax agents handling their own corporation tax submissions in house.
A significant minority of these businesses use third parties in a limited way, often as a quality filter to check completed accounts before filing to HMRC and companies house.
Essentially, unrepresented businesses face increased administrative and financial burdens as they transition to paid for commercial software solutions.
Dormant companies and charities
A company is usually considered dormant for corporation tax if it:
- Has stopped trading and has no other income.
- Is a new limited company that hasn’t started trading.
- Is an unincorporated association or club owing less than £100 corporation tax.
- Is a flat management company.
Accountants managing multiple clients
Accountants and tax agents managing multiple clients will experience substantial workflow changes.
Currently, agents can be appointed for different taxes, with some acting as main agents for certain clients and supporting agents for others.
In general, main agents can fully manage a client’s tax affairs, whereas supporting agents have limited access to tax services and can only view business and property income details.
The closure of the free filing service means these professionals will need to ensure their software solutions can accommodate all client types.
Why HMRC is shutting down the online filing system?
Several critical factors underpin HMRC’s decision to discontinue its joint online filing service for company tax returns.
The existing system, which has served businesses since 2011, faces multiple challenges that necessitate this significant change.
Outdated technology and digital standards
The current filing service has become technically obsolete as digital standards have evolved considerably over the past decade.
HMRC has explicitly stated that the platform “does not meet modern digital standards” or support enhanced corporation tax requirements.
Since its introduction in 2011, the commercial software market has matured and grown substantially.
Today’s tax software solutions offer superior features that the free HMRC service cannot match, including:
- Advanced validation to prevent submission errors.
- Comprehensive tax support and guidance.
- Automated calculations and reminders.
- Integration with other business systems.
Impact of the Economic Crime and Corporate Transparency Act
The Economic Crime and Corporate Transparency Act (ECCT Act) of 2023 has introduced substantial changes to UK company law that the current filing system cannot accommodate.
This legislation brings companies house and the legal framework into line with modern challenges and represents the most significant changes to Companies House since corporate registrations were established in 1844.
The Act gives companies house increased powers to improve the accuracy of information on their registers and to play a more active role in tackling economic crime, which is estimated to cost the UK economy billions annually.
Security and identity verification requirements
The new identity verification processes represent a major component of the ECCT Act reforms. By autumn 2025, all directors and Persons with Significant Control (PSCs) for new incorporations will be required to verify their identity at incorporation.
Existing companies will have a 12-month transition period to provide identity verification credentials when their confirmation statement is due.
These verification requirements are essential as identity fraud in the UK continues to grow yearly meaning HMRC and Companies House must implement robust identity checking systems that the current online filing service cannot support.
The transition to software-based filing is expected to improve data accuracy and integrate with these new security systems.
