The UK is moving towards fully integrated, software-based submissions for corporate reporting, with Companies House – the official register of companies in the UK – to close its web and paper accounts filing routes. Accounts will then need to be filed using commercial software, with the output provided in the Inline eXtensible Business Reporting Language (iXBRL).
This change was originally expected to be implemented in April 2027. However, this date has since been taken off the agenda and the reforms remain under review, with implementation to be confirmed. Either way, companies will be given at least 21 months’ notice to prepare and adjust.
It is important to emphasise that software-only accounts filing is not optional and is not limited to only large or complex companies. Micro-entities, small companies and dormant companies are all within scope. In this article, we discuss:
- The shift to software-based iXBRL filing
- How to maintain UK compliance
- How we can help as an ACSP
- Frequently asked questions
The shift to software-based iXBRL filing
This shift to software-only accounts filing is part of the wider reforms under the Economic Crime and Corporate Transparency Act (ECCTA), which also introduced identity verification requirements for UK directors, limited liability partnership (LLP) members and people with significant control (PSC).
There is a related and earlier change that may affect some companies: the Company Accounts and Tax Online (CATO) service will close on 31 March 2026. This mainly impacts small and micro-entity companies that currently use the service to file both company accounts and corporation tax returns (CT600). The service is being withdrawn because it no longer meets modern digital standards.
Starting 1 April 2026, the CT600 must be filed with the HM Revenue and Customs (HMRC) – the UK’s official tax, payments, and customs authority – using commercial software or through an agent that files using software. The accounts and computations submitted alongside the CT600 will need to be provided in iXBRL format.
With Companies House requiring the same soon, iXBRL will gradually become the practical standard for corporate reporting in the UK.
What is iXBRL?
iXBRL embeds machine-readable tags into a human-readable report. Note that you will not need to “write” iXBRL manually. Rather, your chosen commercial software should generate the iXBRL output as part of the filing process. These tags then enable HMRC and Companies House to validate information more efficiently and process it in a consistent, structured way.
It can therefore influence how a submission is received, reviewed and understood by the authorities. Given this, the choice of software matters and so does having someone who is qualified to prepare and submit the file correctly.
How to maintain UK compliance
The first step is to decide whether you will file in-house or appoint an authorised corporate service provider (ACSP). From there, you can select commercial software that is capable of producing and submitting accounts in the required iXBRL format.
To file in-house, you will need the relevant Companies House software filing account. For many accounts-related submissions, this is a “presenter account”. Where filings attract a fee, a credit account may also be relevant. This is the kind of detail that can delay a filing if it is not put in place early.
With your presenter account and company authentication code, you can begin trialling suitable software in advance. This will allow you to familiarise yourself with the iXBRL output and confirm that the accounts generated are compliant before deadlines apply.
If you’re already using software, it is worth checking whether it supports submission for both HMRC and Companies House under the new rules.
How we can help as an ACSP
From our extensive experience with UK incorporations and ongoing compliance support, this shift to software-only filing is one of the most significant changes to corporate reporting in recent years. Alongside other reforms that increase corporate transparency in the UK, companies need to be diligent in understanding and adhering to the latest requirements. If you would like help assessing your readiness, reach out to our team.
As a Companies House authorised agent, we have the necessary credentials and are qualified to help you. Once the CATO service is closed, our UK team can work with you to complete your CT600 filing via the approved software routes. We can continue managing your company’s overall submission with both HMRC and Companies House in the required iXBRL format.
This means your internal team does not need to purchase, learn and maintain commercial software. You will also have a clearer, repeatable filing process each year. Support can also be provided if you need to amend a previous submitted return or refile after a rejection.
The technical workload can therefore be handled by our team, with minimal disruption to your day-to-day operations. If this sounds like the approach your business would prefer, please get in touch.
Frequently asked questions
Can I still file paper accounts if I pay a higher fee?
No. As this will be a hard regulatory change, Companies House will no longer accept paper accounts, regardless of whether a higher fee is offered. Once implemented, accounts must be submitted through commercial software that connects directly to Companies House.
Will micro-entities be exempt from filing a profit and loss account?
No, there are no exemptions based on company size. Micro-entities will be required to file a full set of accounts, including the profit and loss account, which will become publicly available on the Companies House register.
Will dormant companies need software to file accounts?
Yes. Dormant companies are not exempt from the software-only mandate. Even though dormant accounts are simpler, they are still statutory accounts and must be filed with Companies House. Once WebFiling and paper routes are withdrawn, dormant companies will also need to use software or appoint an ACSP to file on their behalf.
Does a UK branch need to file accounts?
Yes, a UK branch of an overseas company is still required to file accounts with Companies House. The exact filing requirements depend on the nature of the overseas entity and whether it prepares accounts under its home jurisdiction rules but filings must still be made in the UK.
As the system switches to software-only filing, UK branches will also need to ensure they can submit the required documents digitally, either through suitable software or via an ACSP. If you would like us to review your branch position and confirm what needs to be filed, get in touch and we can assist.
What happens if you don't file company accounts in the UK?
Late filing may result in automatic financial penalties, which increase the longer the delay continues. Persistent non-compliance can also trigger enforcement action against the directors, including fines.
In addition, Companies House has the authority to strike a company off the register if accounts are repeatedly not filed. The move to software-only filing does not reduce these obligations; if anything, it increases scrutiny. If you would like us to help you set up a reliable filing process and stay on top of deadlines, get in touch.
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