Companies House 2026: Navigating Mandatory Digital Filing & ECCTA Reforms

The Immediate Shift: Mandatory Commercial Software for Corporation Tax Filing

The landscape of UK corporate compliance underwent a significant transformation on 31 March 2026. On this date, the free joint online filing service for company accounts and Corporation Tax (CT600) returns, previously offered by HMRC and Companies House (often known as the CATO portal), was permanently closed.

This closure marks a critical juncture for UK businesses and, by extension, for the accounting practices that serve them. From 1 April 2026, all companies are now mandated to use commercial software for submitting their Corporation Tax returns to HMRC. There is no longer a free HMRC web form for companies, except in very narrow 'reasonable excuse' cases where paper filing might be permitted.

Why the Free Service Was Withdrawn

HMRC's decision to withdraw the CATO portal stems from its inability to meet modern digital standards and align with the broader reforms introduced by the Economic Crime and Corporate Transparency Act (ECCTA) 2023. The government's drive is towards greater digital transformation, improved data quality through software validation, enhanced transparency on company registers, and a reduction in economic crime.

Commercial software solutions are designed to offer superior validation, comprehensive support, and automated reminders, which are crucial for maintaining compliance in an increasingly complex regulatory environment. This shift also encourages the use of iXBRL-tagged accounts and computations, which facilitate more efficient data processing and validation by the authorities.

Implications for Practices and Clients

Mandatory Software Adoption: Practices must ensure all clients filing Corporation Tax returns are using HMRC-recognised commercial software. This is a non-negotiable requirement.
Historical Data Access: Crucially, past filings submitted via the CATO portal will no longer be accessible online after 31 March 2026. Practices should have advised clients to download and save at least three years' worth of historical returns and accounts for their records.
Cost Considerations: For many micro-entities and small businesses that previously relied on the free service, this change introduces a new operational cost. Accountants can help clients understand these costs and choose appropriate software.

Key Takeaway: The era of free Corporation Tax filing is over. From 1 April 2026, commercial software is essential for all CT600 submissions. Ensure your practice and clients are fully transitioned and have retained historical filing data.

ECCTA's Broader Impact: Transforming Companies House

The Economic Crime and Corporate Transparency Act 2023 (ECCTA), which received Royal Assent on 26 October 2023, represents the most significant reform to UK company law in decades. Its overarching aim is to enhance transparency, combat economic crime, and improve the reliability of the UK's corporate register.

ECCTA fundamentally transforms Companies House from a largely passive recipient of information into an active, verifying 'gatekeeper' with substantial new powers and responsibilities. This shift impacts various aspects of company administration, from filing processes to identity verification and data accuracy.

Digital Accounts Filing: The Confirmed Pause and What It Means for Practices

While the move to commercial software for Corporation Tax is a firm deadline, the plans for mandatory digital accounts filing under ECCTA have seen a significant, albeit temporary, change. Companies House had initially indicated that all company accounts would need to be filed exclusively via commercial software from 1 April 2027, ending web and paper submissions.

However, Companies House updated its guidance on 28 January 2026, confirming that these filing reforms will not be introduced in April 2027 as previously planned. The measures are currently under review, and a final decision on the timing will be announced in due course.

Current Status and Future Outlook

No Immediate Change: Companies can continue to file their annual accounts using existing methods – Companies House WebFiling, paper submissions, or commercial software – until further notice.
Extended Notice Period: Companies House has committed to providing at least 21 months' notice before any new mandatory digital accounts filing requirements come into force. This suggests that the earliest such changes could take effect is likely 2028.
Abridged Accounts and P&L: Proposals to abolish abridged/filleted accounts and require small and micro-entities to file a profit and loss account (P&L) are also part of the review. Practices should monitor updates, but there is no immediate requirement to change current filing practices for these entities.

This delay offers a welcome reprieve for many practices and their clients, particularly those who were concerned about the readiness of suitable software solutions or the administrative burden. However, it is crucial to remember that this pause applies *only* to accounts filing; the 1 April 2026 deadline for mandatory commercial software for Corporation Tax returns remains firmly in place.

Strengthening Transparency: Understanding Identity Verification Requirements

A cornerstone of ECCTA is the introduction of mandatory identity verification (IDV) for individuals involved with UK companies. This is a crucial step to increase transparency and combat the misuse of corporate structures.

Who Needs to Verify and When

Directors and Persons with Significant Control (PSCs): IDV became mandatory for new directors and PSCs upon incorporation or appointment from 18 November 2025. Their identity must be verified before their appointment can be registered.
Existing Directors and PSCs: Existing directors and PSCs have a 12-month transition period, also starting 18 November 2025, to complete their identity verification. This is generally linked to their company's next annual confirmation statement.
Presenters of Filings: By Spring 2026, IDV will be compulsory for any individual presenting documents to Companies House. This includes company secretaries and other authorised 'presenters'.
Authorised Corporate Service Providers (ACSPs): Third-party agents who file on behalf of others must be registered as an ACSP and will be responsible for verifying the identity of their clients to the statutory standard. ACSPs must retain identity verification records for seven years.

How to Verify Identity

There are generally three approved routes for identity verification:

Directly with Companies House: Individuals can complete the IDV check online via the UK government website, typically using a GOV.UK One Login account, by submitting an identity document (e.g., biometric passport, UK photocard driving licence) and a live photo.
Via an Authorised Corporate Service Provider (ACSP): An ACSP can carry out the verification checks using approved technology or processes and confirm the outcome to Companies House.
Through the Post Office: Individuals can initiate the process online and then attend a participating Post Office branch with valid ID for verification and a live photo.

Once verified, Companies House will issue a unique personal authentication code, which will be required for all future filings. Non-compliance with IDV requirements can lead to significant financial penalties for both the individual and the company.

New Foundations: Registered Office and Email Address Rules

Beyond digital filing and identity verification, ECCTA has also introduced stricter requirements for company addresses, which came into force on 4 March 2024.

'Appropriate' Registered Office Address

All companies must maintain an 'appropriate address' as their registered office. This means the address must be:

A physical address in the UK.
In the same country (jurisdiction) where the company is incorporated.
An address where documents delivered by hand or post would be expected to come to the attention of a person acting on behalf of the company.
An address where the delivery of documents is capable of being recorded by an acknowledgement of delivery.

Crucially, traditional PO Box addresses are no longer permitted as a standalone registered office address. If Companies House determines an address is not appropriate, they have the power to change it to a default address and may initiate strike-off proceedings if a compliant address is not provided within 28 days. This highlights the importance of regular checks on registered office obligations.

Mandatory Registered Email Address

Companies are also now required to provide an 'appropriate' registered email address to Companies House. This email address will be used by Companies House for official communications but will not be publicly available. New companies incorporated after 4 March 2024 must provide this upon incorporation, while existing companies need to provide it when they file their next confirmation statement with a statement date on or after 5 March 2024.

Enhanced Enforcement: Companies House's New Powers and Penalties

The ECCTA has significantly bolstered Companies House's powers, transforming its role from a passive registrar to a more active and robust regulator. These changes are designed to improve data integrity and deter economic crime.

Key Powers and Sanctions

Querying and Rejecting Filings: Since 4 March 2024, Companies House has had enhanced authority to query any information submitted, request further evidence, and reject or remove suspicious, inaccurate, or fraudulent data from the register.
Civil Financial Penalties: From 2 May 2024, Companies House gained the power to impose civil financial penalties of up to £10,000 for most offences under the Companies Act 2006. This significantly broadens the scope of non-compliance that can incur a penalty and aims to ensure prompt adherence to requirements.
Increased Fees: To fund these enhanced measures, Companies House increased various fees from 1 May 2024, and further increases took effect from 1 February 2026. This includes incorporation fees and confirmation statement fees, with paper filings becoming even more expensive to encourage digital adoption.
New Criminal Offences: ECCTA introduced a new criminal offence of 'failure to prevent fraud', which came into force on 1 September 2025. Companies can be liable if an associate commits fraud intending to benefit the organisation, and the organisation did not have reasonable prevention procedures.
Data Sharing: Companies House now has greater ability to share data with UK law enforcement agencies and regulatory bodies.

The increase in staff at Companies House underscores a more assertive approach to enforcement. Practices must be acutely aware of these heightened risks and ensure their clients are fully compliant to avoid fines and potential criminal prosecutions for directors.

Actionable Steps for UK Practices: Staying Ahead of Compliance

Navigating the evolving landscape of Companies House and ECCTA reforms requires proactive management. Here are practical actions for accounting and bookkeeping firms:

Review Corporation Tax Filing Processes: Ensure all clients are transitioned to HMRC-recognised commercial software for CT600 submissions from 1 April 2026. If any clients were still using the CATO portal, verify they have downloaded historical data.
Communicate Digital Accounts Filing Status: Inform clients about the confirmed pause on mandatory software-only accounts filing for April 2027. Reassure them that existing filing methods remain valid for now, but advise them to still prepare for an eventual transition.
Address Identity Verification: Systematically identify all directors, PSCs, and LLP members across your client base who need to complete IDV. Advise new appointees to complete this before registration, and existing individuals to do so within the 12-month transition period (starting 18 November 2025), ideally before their next confirmation statement. Ensure your firm is prepared for presenter IDV by Spring 2026.
Verify Registered Office and Email Addresses: Conduct a review of all client registered office addresses to ensure they meet the 'appropriate address' definition. Advise any clients using PO Boxes to update their address immediately. Confirm all clients have provided an appropriate registered email address to Companies House.
Update Internal AML Compliance and Procedures: Given the ECCTA's focus on economic crime, review and update your firm's AML compliance procedures, particularly around client due diligence and beneficial ownership verification.
Budget for Increased Fees: Factor the increased Companies House filing fees (effective 1 February 2026) into client billing and internal financial planning.
Stay Informed: Regularly monitor official Companies House and government guidance for further updates on ECCTA implementation, especially regarding the future of digital accounts filing and any additional requirements.

Embracing Digital Solutions for Future Compliance

The changes introduced by ECCTA and the move away from free government filing services underscore the undeniable shift towards a fully digital compliance ecosystem. For practices, this isn't merely about meeting new rules; it's an opportunity to enhance efficiency and client service.

Robust commercial accounting and compliance software can streamline processes for Corporation Tax, manage company secretarial duties, track identity verification statuses, and help maintain accurate registered office details. By automating routine tasks and providing built-in validation checks, digital tools can significantly reduce the risk of errors and non-compliance, allowing your team to focus on higher-value advisory work.

Investing in integrated platforms that offer comprehensive solutions for Companies House filings, tax returns, and client management will be key to navigating these ongoing reforms successfully and ensuring seamless compliance for your UK practice and its clients.

Conclusion

The year 2026 marks a pivotal moment for UK corporate compliance. The immediate requirement for mandatory commercial software for Corporation Tax filing, coupled with the ongoing phased implementation of the Economic Crime and Corporate Transparency Act, demands careful attention from accounting and bookkeeping practices.

While the pause on mandatory digital accounts filing for April 2027 offers a temporary reprieve, the overarching direction is clear: increased transparency, stricter enforcement, and a fully digitised environment. By proactively addressing these changes, leveraging appropriate digital tools, and staying informed, practices can ensure their clients remain compliant and mitigate the risks associated with this transformative period.