Companies House 2026 Changes: CATO Shutdown Means You Now Need Premium iXBRL Software
What Happened in April 2026?
On 1 April 2026, the UK government officially shut down CATO (Companies House Authentication and Tagging Online) – the free iXBRL tagging tool used by thousands of small businesses and accountants.
Why?
Companies House said CATO was outdated, insecure, and unable to support modern iXBRL taxonomies. They will not replace it with another free tool.
What Does This Mean for Your Company?
If you previously used CATO to tag accounts, you must now use premium (paid) iXBRL software to file your annual accounts. Filing with PDF or old iXBRL formats will be rejected.
Which Software Should You Use Now?
Here are the most popular CATO alternatives:
| Software | Price (approx) | Best For |
|---|---|---|
| QuickXBRL | £99/year | Small businesses |
| IRIS | £250+/year | Accounting firms |
| Taxfiler | £150/year | Freelance accountants |
| DigiAccounts | £120/year | Micro entities |
Why Is There No Free Government Alternative?
Companies House states: “Maintaining a free tagging tool is no longer viable. The private sector now offers affordable, high-quality solutions.”
In plain English: the government wants you to buy from approved software vendors.
What If You Don’t Convert to iXBRL?
- Companies House will reject your filing
- Late filing penalties apply (£150 – £1,500+)
- Your company could be struck off the register
How to Switch from CATO to Premium Software
- Export your last set of accounts from your records (Excel or PDF)
- Sign up for QuickXBRL or another tool
- Convert your accounts to iXBRL
- File directly to Companies House from the software
- Keep the software for next year
FAQ
A: Yes. As of April 2026, it is offline and will not return.
A: No. All compliant iXBRL software requires a paid subscription or one-off fee.
A: Arelle is free but requires technical skill. It is not supported by Companies House.
A: As little as £99 per year – less than one late filing penalty.