The basics
From 18 May 2026, HMRC requires formal registration for anyone who interacts with them on behalf of paying clients. This includes most accountants in practice, even if tax advice isn't your core business.
If you file returns, handle queries, or call HMRC about client matters, you're in scope. The three-month transition period starts in May, August, or November depending on your service type.
Registration timelines
- 18 May 2026: All agents may apply early
- 18 August 2026: Self-Assessment and Corporation Tax agents must register
- 18 November 2026: Payroll-only agents must register
You get three months post-deadline to secure your Agent Services Account while continuing HMRC interactions. After that, unregistered agents cannot act.
What HMRC checks
Tax compliance: Your own returns must be current, liabilities paid, or payment plans maintained. You'll be held to the standards you expect from clients.
AML supervision: Confirm proper supervision through a professional body or HMRC's Estate and Corporate Enquiries unit. Payroll providers without designated supervisory bodies must register with ECU separately.
Professional conduct: Meet HMRC's Standard for Agents (competence, honest behaviour, good records, cooperation, system integrity).
Clean record: No insolvency, fraud convictions, HMRC bans, or anti-avoidance sanctions.
For firms with five or fewer officers, all relevant individuals face checks. Larger firms follow a stepwise process.
Consequences
Non-compliance brings £5,000+ fines, suspension, or prohibition from acting as an agent. HMRC published initial guidance on 17 February 2026.
Exemptions (limited)
Most in-house tax teams dealing only with employer affairs, software providers with no advisory role, certain customs-only intermediaries, and certain appeals-only work may be exempt. If you serve external clients, assume registration applies.
What to do now
Review your tax compliance position, AML supervision status, and existing agent setups. Prepare documentation. Don't wait until the transition period closes.