Authorising an accountant to deal with HMRC

Authorising an accountant allows specified dealings with HMRC but does not transfer responsibility for the accuracy of your information. Use the official agent authorisation route and agree exactly which services, tax periods and communications are covered.

Never share personal sign-in credentials as a substitute for authorisation. Confirm who receives notices, who approves returns and how the arrangement ends or changes.

Agree the work before granting access

Identify whether the accountant will prepare a return, discuss an enquiry, manage a particular tax service or provide advice only. Record the tax periods and any historic issues included. An engagement described broadly as accounts support may not cover personal Self Assessment, an appeal or correspondence about an older liability.

HMRC provides official ways to appoint someone to deal with tax affairs. ^[1] Use the route appropriate to the service and relationship. A signed engagement letter and HMRC authorisation serve different purposes: one describes the professional work, while the other enables specified dealings with HMRC. Keep both clear instead of assuming either document automatically completes the other process.

Check the adviser and current registration position

Verify the identity of the firm and the person responsible for the work through reliable professional and business information. Ask about competence for the particular issue, especially overseas income, complex reliefs or disputes. A familiar trading name should not replace checking the actual entity receiving authority and confidential information.

HMRC's mandatory tax-adviser registration requirements are being introduced in stages during 2026 and 2027, with timing depending on the adviser's circumstances. ^[2] Ask the firm to confirm its applicable position. Do not confuse that firm-level requirement with a particular client's authorisation, or treat registration alone as proof of specialist competence or approval of every piece of advice.

Use the correct authorisation process

Follow the official instructions and confirm the taxes or services covered. Different HMRC services can use different agent arrangements. Read an authorisation request before accepting it, and verify an unexpected request with the adviser through an established contact route. Avoid sending codes or sensitive information in response to an unverified message.

Never give the adviser your personal sign-in credentials as a substitute for proper authority. Keep account recovery information under your own control. If assistance is needed with an online process, agree a method that preserves the individual's ability to access their account independently and does not leave the firm using a shared personal login indefinitely.

Decide who handles notices and approvals

Agree who monitors HMRC letters and online messages, who supplies documents and who approves submissions. Some correspondence may still reach the taxpayer even when an agent is appointed. Forward relevant notices promptly through a secure route and record any deadline rather than assuming the adviser automatically received an identical copy.

Keep the final approval separate from routine questions during preparation. The taxpayer should know which version will be submitted and have an opportunity to correct factual errors. Use Avoiding last-minute tax return problems to build an approval timetable and Preparing for your first tax return for the evidence needed for a complete return. Authorisation does not make missing or inaccurate information reliable simply because an accountant enters it into software.

Control documents and the end of the engagement

Agree how records will be transferred, stored and returned, and what the client will receive after filing. Keep copies of returns, computations and acknowledgements that remain accessible independently of the firm's portal. Identify any documents or access needed if the firm closes, the relationship ends or another adviser takes over.

When changing advisers, confirm who completes work already underway and who deals with outstanding correspondence. Review and update the relevant authority through the official process, while preserving a clear handover. Removing access without resolving an imminent filing task can create a gap; leaving old authority unreviewed can create uncertainty about who is acting for the taxpayer.

For Self Assessment tax return support, explain the taxes, years and decisions for which support is required. Ask for the scope, fees, third-party costs and responsibilities in writing. Identify any urgent notice at the outset and confirm whether representation on that matter is included. Keep the authorisation evidence with the engagement record so the relationship can be understood without relying on verbal assurances.

Periodically review whether the arrangement still matches the work being performed. A business may add payroll, VAT or digital reporting after the original engagement, while the existing authority covers only another service. Record each change deliberately and confirm the person responsible. This prevents a familiar adviser relationship from concealing an administrative gap in a newly added tax obligation.

Illustrative scenario

A sole trader appoints an accountant for Self Assessment but continues handling VAT elsewhere. Their engagement and authorisations identify the separate responsibilities so neither adviser assumes the other is filing a return.

Preparation checklist

• Confirm the service scope
• Use official authorisation
• Agree approval responsibilities
• Record notice-handling arrangements