Accountants across the UK are telling clients this month to start planning for a filing overhaul that Companies House confirmed back in June but that has only started showing up in client meetings and professional briefings in earnest through August: from 1 April 2028, every UK-registered company will have to file its annual accounts using commercial software, in a digital format called iXBRL, and the web-based and paper filing routes that millions of small businesses currently use will close for accounts altogether. The reform, originally due in April 2027, was pushed back a year after Companies House consulted with businesses and professional bodies on the impact of the changes, giving companies what the register describes as one full accounting year plus nine months — 21 months in total — to get ready.
What Companies House confirmed
The announcement, published as a Companies House news story on 9 June 2026, sets out how the government intends to implement the accounts-reporting measures contained in the Economic Crime and Corporate Transparency Act 2023. Under the confirmed package, all UK companies will be required to file their accounts through commercial software rather than Companies House's own WebFiling service or by post; small companies and micro-entities will, for the first time, have to file a profit and loss account; abridged accounts will no longer be an option for any company; and directors claiming an audit exemption will need to give a strengthened statement confirming which exemption applies and why the company qualifies.
None of this is new in substance — the underlying law has been on the books since October 2023 — but the June announcement fixed the date and confirmed which parts of the original proposal survived stakeholder pushback largely intact, and which were softened. The clearest concession is on publication: small companies and micro-entities will have to prepare a profit and loss account, but they will be given the option to opt out of having it published on the public register, addressing concerns from smaller businesses about competitors or landlords seeing their margins.
Why the timeline moved to April 2028
Companies House said the extra year reflects direct feedback from the software industry and from businesses that raised concerns about the practicality of the original April 2027 date, particularly around the availability of compatible accounting software and the time needed to test new filing processes before they become mandatory. The Institute of Chartered Accountants in England and Wales welcomed the confirmation of a fixed date after months of uncertainty, and its guidance to members this summer has focused on treating 21 months as a working deadline rather than a distant one — software procurement, staff training and client communication all take longer than firms expect once a hard cut-off is in place.
That framing is exactly why the story has resurfaced in August rather than staying a one-off June news item. Accountancy practices generally run their busiest client conversations around this time of year, once the summer self-assessment lull ends and firms turn to year-end planning for clients with December and March accounting reference dates, and several have used those conversations to flag the 2028 changes now precisely because software selection and internal testing are not tasks that can be left until the final few months.
Software-only filing in iXBRL
From April 2028, Companies House's web and paper filing routes will close specifically for accounts — they will remain open for other statutory filings, including confirmation statements and updates to director or PSC details. Every company, whether it files its own accounts or uses an accountant or other third-party agent, will need accounts prepared and submitted in Inline eXtensible Business Reporting Language, a machine-readable format already used for tax filings to HMRC but not, until now, mandatory for the accounts side of Companies House filings.
Companies House has published a software finder tool on GOV.UK listing approved commercial providers, and says it will write to every company directly at its registered email address to explain the change and point to available guidance. Most accounting software already used for HMRC's Making Tax Digital obligations can produce iXBRL output, which means companies that already file digitally with HMRC are likely to need comparatively little new infrastructure — the bigger adjustment falls on the minority still filing accounts on paper or through the free WebFiling portal, who will need to select and test a commercial package before the window closes.
No more abridged accounts, and a new profit and loss requirement
Two changes affect small companies and micro-entities more than any others in the package. First, the option to file abridged accounts — a simplified format that combines several profit and loss line items, including turnover, into a single "gross profit or loss" heading — is being removed entirely from April 2028. Second, small companies and micro-entities will be required to file a full profit and loss account alongside their balance sheet, something they have been able to omit or heavily simplify for years under existing small-companies exemptions.
Under the confirmed rules, a micro-entity will need to file a balance sheet, a profit and loss account, and an auditor's report unless the company is exempt from audit. A small company will need to file a balance sheet, a directors' report, a profit and loss account, and an auditor's report where audit exemption doesn't apply — though Companies House has separately indicated that a parallel change under the government's Modernising Corporate Reporting programme is expected to remove the directors' report requirement for companies of all sizes, which would supersede that specific line item before it takes full effect. Companies are also being restricted on how often they can shorten their accounting reference period, with a business reason required if a company wants to shorten it more than once within five years — a measure Companies House says targets the practice of manipulating year-end dates to obscure financial information or delay a filing deadline.
An opt-out from publication, not from disclosure
The opt-out mechanism for small companies and micro-entities applies only to what appears on the public register, not to what Companies House itself holds on file. Where a company opts out of publishing its profit and loss account, Companies House, HMRC and law enforcement bodies will still have access to that data for the purposes of identifying and addressing economic crime and tax evasion — the confidentiality only extends to the version of the register that competitors, journalists, landlords and credit-reference agencies can search. Companies House has not yet confirmed exactly how the opt-out will be exercised on a filing, saying only that further details will follow in guidance ahead of the 2028 start date.
Part of a wider pattern for UK companies in 2026
The accounts reforms are the third major piece of ECCTA-driven change working through Companies House this year, alongside the phased rollout of mandatory identity verification for directors and people with significant control that began in November 2025, and the migration of WebFiling sign-in to GOV.UK One Login that has been under way since October 2025. Firms handling company secretarial work for multiple clients are now dealing with identity checks, a new sign-in system and a 2028 accounts deadline more or less simultaneously, which is one reason professional bodies have been keen to separate the accounts timeline clearly from the identity verification one — the two run on different clocks and carry different penalties for getting them wrong.
Companies House's own account of the reform programme frames all three strands as working toward the same goal: more accurate, more verifiable information on the companies register, and a smaller opening for the kind of shell-company and false-filing activity that has previously gone undetected because nobody was checking who filed what, or whether the numbers behind an abridged balance sheet stood up to scrutiny.
What to do before 2028
Companies that already use accounting software to meet Making Tax Digital obligations for VAT or income tax are, in most cases, already most of the way there — the practical task is confirming with the software provider that iXBRL output for Companies House filings is on their roadmap, and when. Companies still filing accounts on paper or through the free WebFiling service have more ground to cover, and Companies House's own advice is to check the software finder list, apply for a presenter account if one will be needed, and have the company's authentication code ready well before the final year of the transition begins.
Twenty-one months sounds like a long runway for a filing change most companies only think about once a year. It stops looking that way the moment a director realises their accounting reference date falls in the first quarter after the switch, leaving no cushion to fix a rejected software filing before the statutory deadline arrives.