CATO Is Closing: What Accountants Need to Know Before 31 March 2026

If you run an accounting practice in the UK, there is a critical deadline approaching that you cannot afford to ignore. HMRC's Centralised Agent Team Operations (CATO) register — the system through which accounting agents have been authorised to act on behalf of clients — is closing. The transition to the new Authorised Corporate Service Provider (ACSP) framework under Companies House oversight must be completed by 31 March 2026.

What Is CATO and Why Is It Closing?

CATO has been HMRC's central team for managing agent registrations and authorisations. When you registered as a tax agent with HMRC, it was CATO that processed your application, issued your agent reference numbers, and managed the 64-8 authorisation process that allows you to act on behalf of your clients.

The closure of CATO is part of a broader government initiative to modernise corporate governance and anti-money laundering (AML) supervision in the UK. Under the Economic Crime and Corporate Transparency Act 2023, Companies House is taking on enhanced powers to verify the identities of those involved in company formation and management. The ACSP framework is a key part of this.

What Is an ACSP?

An Authorised Corporate Service Provider (ACSP) is the new designation for businesses that provide trust or company services. This includes accountants, tax advisers, company formation agents, and other professionals who file documents with Companies House on behalf of clients.

To become an ACSP, your practice must be supervised for anti-money laundering purposes by a recognised supervisory body such as HMRC, ACCA, ICAEW, AAT, or one of the other approved bodies. You must also register directly with Companies House and verify your identity through their new identity verification system.

What Happens If You Miss the Deadline?

If your practice has not transitioned to ACSP status by 31 March 2026, you will lose the ability to file documents with Companies House on behalf of clients. This means no more annual confirmation statements, no company formations, no changes of director or registered office — none of the routine filings that many practices handle as part of their standard service offering.

More critically, you may also face disruption to your HMRC agent authorisations. While HMRC has stated that existing 64-8 authorisations will continue to function during the transition period, any new authorisation requests or changes to existing ones may be affected if your agent status is not aligned with the new framework.

What You Need to Do NOW

The transition involves several steps, and some of them take time. Do not leave this to the last minute.

1. Confirm Your AML Supervision

Ensure your practice is registered with and supervised by an approved AML supervisory body. If you are supervised by HMRC for AML purposes, check that your registration is up to date and that all relevant individuals in your practice are named on the registration.

2. Register for Identity Verification

All directors and key personnel in your practice will need to verify their identity with Companies House. This can be done digitally, by video call, or in person. TaxStats ID offers all three verification options: Digital (£39), Video (£49), or In-Person (£59).

3. Apply for ACSP Status

Once your AML supervision is confirmed and identity verification is complete, you can apply for ACSP status through the Companies House online service. The application requires details of your practice, your supervisory body, and the services you provide.

4. Update Your Systems

Ensure your practice management software supports the new filing requirements. Some older software packages may not be updated in time. TaxStats is fully ACSP-compliant and handles all Companies House filing requirements through the new framework.

How TaxStats Handles ACSP Compliance

TaxStats has been updated to support the full ACSP framework from day one. Our platform handles Companies House filings through the new authorised channel, includes built-in identity verification through TaxStats ID, and maintains full audit trails for AML compliance purposes.

For practices that are migrating from other software, we provide dedicated migration support to ensure continuity of service throughout the transition. Our team has helped dozens of practices through the CATO-to-ACSP transition and can guide you through every step.

Timeline and Action Steps

• Now — February 2026: Confirm AML supervision, begin identity verification for all directors
• February 2026: Submit ACSP application to Companies House
• March 2026: Verify ACSP status is confirmed, test filing capabilities
• 31 March 2026: CATO register closes — all agents must be operating under ACSP framework

Conclusion

The closure of CATO is not optional and the deadline is not flexible. Every accounting practice that files with Companies House or acts as a tax agent needs to complete the transition to ACSP status before 31 March 2026. Start the process now to avoid last-minute complications.

If you need help with identity verification, ACSP registration, or migrating your practice to a compliant platform, contact TaxStats. We are an HMRC Recognised Agent and ACCA Chartered practice, and we have the tools and expertise to ensure your practice is ready.