Can you change accountant during an HMRC enquiry

Q: Who needs to be told about the change?

The officer running the enquiry. Write to them, or have the new adviser write once authorised, so letters and calls go to the right place. CC/FS1a says HMRC may still need to contact you directly about some things and will copy letters to your representative. The tribunal, if an appeal is already there. Rule 11 of the First tier Tribunal (Tax Chamber) rules requires written notice of a representative's name and address to the tribunal and the other party. The tribunal and HMRC may assume a representative remains authorised until told in writing that this is not so, so a change must be notified, not just made. The old accountant. They need your authority to discuss your affairs with the new adviser, and the new adviser will normally write to them before accepting the work; see professional clearance when changing accountant.

Q: How do you avoid missing a deadline during the handover?

List every live date on day one: the due date for the latest information request, any Schedule 36 notice, any 30 day appeal or review window, and in a fraud case the 60 day Code of Practice 9 deadline. Ask for more time before the date passes. The Enquiry Manual (EM1580) encourages officers to allow at least 30 days for informal requests and to be flexible where warranted, and CC/FS1a says HMRC may agree extra time for a good reason. A change of adviser with a clear handover plan is a reason worth putting to the officer; see asking HMRC for more time. Know the cost of missing a formal notice. Failing to comply with an information notice carries a £300 penalty under paragraph 39 of Schedule 36 to the Finance Act 2008. Paragraph 45 gives a reasonable excuse defence, but reliance on another person only counts if you took reasonable care. HMRC's guidance on reasonable excuse (CH160700) does give, as one example that may count, a delay in getting paperwork from a previous adviser after engaging a new one.

Yes. You have the right to be represented by anyone you choose, and you can switch adviser part way through an HMRC enquiry. The enquiry does not pause while you do, so the practical work is getting the new adviser authorised for the check, moving the file across, and making sure no response date or appeal deadline is missed in the handover.

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Can you change accountant while HMRC is checking your return?

HMRC’s compliance check factsheet CC/FS1a lists the right to be represented, and says you can appoint anyone to act for you. Nothing in the enquiry rules ties you to the adviser who prepared the return. People switch because the original accountant made the error under review, because the enquiry needs a specialist, or because the relationship has broken down.

Two things do not change. You remain responsible for your own tax affairs, and CC/FS1a reminds taxpayers that with an adviser they must still take reasonable care that what is sent on their behalf is correct. And HMRC’s timetable keeps running: the officer’s information request dates, any formal notice periods and the 30 day window to challenge a decision all continue regardless of who is acting.

How does the new accountant get authorised?

HMRC’s Compliance Handbook (CH201550) says valid and specific authorisation must be in place before a compliance officer can deal directly with an adviser. There are two routes.

Route	What it covers	Effect on the old accountant
Full agent authorisation (digital handshake, Online Agent Authorisation, the client’s business tax account or form 64 8, depending on the tax)	Day to day dealings for that tax, including the enquiry	HMRC says any new authority received will replace any existing authority
Form Comp1, temporary authorisation for a compliance check	Only the compliance check named, including any extension of it to other taxes or periods	Does not replace or amend an existing authorisation, so the old accountant stays authorised for day to day work

CH201550 sets out how Comp1 works. It can extend an existing authorisation to other taxes being checked, appoint a specialist for the check while the existing adviser keeps the day to day work, or appoint an adviser solely for the check. It ends when the check is closed and any related appeals are resolved. If you have agreed to email contact with HMRC, the form can be sent straight to the caseworker. A Comp1 can be cancelled verbally, and changing it needs a new form. For the paper authorisation route, see form 64 8.

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Should you keep the old accountant for everything else?

That is a choice, and Comp1 exists partly to make it possible. A common pattern is to bring in a specialist for the enquiry on a Comp1 while the existing firm carries on with returns and payroll. CH201550 tells caseworkers to be vigilant about data security where more than one adviser is acting, so make sure the officer knows who handles what.

If instead you are leaving the old firm entirely, a new full authorisation will replace the old one for that tax. You can also remove the old agent yourself through your business or personal tax account, and HMRC’s guidance warns that removing an agent from Self Assessment and from Making Tax Digital for Income Tax are separate steps. See how a client removes their agent.

Who needs to be told about the change?

The officer running the enquiry. Write to them, or have the new adviser write once authorised, so letters and calls go to the right place. CC/FS1a says HMRC may still need to contact you directly about some things and will copy letters to your representative.
The tribunal, if an appeal is already there. Rule 11 of the First tier Tribunal (Tax Chamber) rules requires written notice of a representative’s name and address to the tribunal and the other party. The tribunal and HMRC may assume a representative remains authorised until told in writing that this is not so, so a change must be notified, not just made.
The old accountant. They need your authority to discuss your affairs with the new adviser, and the new adviser will normally write to them before accepting the work; see professional clearance when changing accountant.

What does the new accountant need from the old one?

The enquiry file, not just the books. That means HMRC’s opening letter and every later information request, the replies already sent with their enclosures, notes of any meetings or calls with the officer, the computations and working papers behind the return under enquiry, any penalty explanation or behaviour discussion, and any agreed timetable. Without the replies already sent, the new adviser risks contradicting earlier answers, which can damage the quality of disclosure.

Records you supplied to the old accountant are generally yours, but an accountant may in some cases hold papers under a particular lien for unpaid fees. Resolve any fee dispute early rather than in the week a reply is due. See accountant’s lien over client records.

How do you avoid missing a deadline during the handover?

List every live date on day one: the due date for the latest information request, any Schedule 36 notice, any 30 day appeal or review window, and in a fraud case the 60 day Code of Practice 9 deadline.
Ask for more time before the date passes. The Enquiry Manual (EM1580) encourages officers to allow at least 30 days for informal requests and to be flexible where warranted, and CC/FS1a says HMRC may agree extra time for a good reason. A change of adviser with a clear handover plan is a reason worth putting to the officer; see asking HMRC for more time.
Know the cost of missing a formal notice. Failing to comply with an information notice carries a £300 penalty under paragraph 39 of Schedule 36 to the Finance Act 2008. Paragraph 45 gives a reasonable excuse defence, but reliance on another person only counts if you took reasonable care. HMRC’s guidance on reasonable excuse (CH160700) does give, as one example that may count, a delay in getting paperwork from a previous adviser after engaging a new one.

Does changing adviser affect penalties?

Not directly, but it can affect the reduction for disclosure. CC/FS1a explains that HMRC looks at how much you help it during the check, telling, helping and giving access, and how long it took you to tell HMRC what was wrong. A switch that stalls the enquiry for months, or that produces answers inconsistent with earlier ones, can count against you. If the new accountant finds further errors, telling the officer promptly helps rather than hurts.

How might a mid enquiry switch work?

Illustration only. HMRC opens an enquiry into a landlord’s return in March, and the officer asks for rental records by 30 April. On 10 April the landlord decides to move to a new firm. The new firm sends the landlord a Comp1 to sign that day and, with consent, writes to the old firm asking for the enquiry correspondence and working papers. It also writes to the officer explaining the change, confirming the 30 April date is known, and asking for two extra weeks to review the file. The old firm keeps the day to day authorisation until the year end, when the landlord gives the new firm a full authorisation, which replaces the old one.

What mistakes come up most often?

Assuming HMRC will extend deadlines automatically because the adviser has changed.
Sending a 64 8 when a Comp1 was intended, or the reverse, and ending up with the wrong firm on HMRC’s records.
Not telling the tribunal about a new representative in an appeal already lodged.
The new adviser replying before seeing what the old one already told HMRC.
Leaving the old firm’s authorisation in place by mistake after the relationship has ended.

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Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 24 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.