When someone who is not your client asks for your view on how tax law or accounting or auditing standards apply to a situation another accountant is already handling, section 321 of the ICAEW Code of Ethics treats it as a second opinion. You must confirm any oral opinion in writing, make clear that an opinion on a hypothetical situation is limited to that situation, and normally seek permission to contact the existing accountant. If the entity refuses, you must decide whether you can give the opinion at all, and declining is generally appropriate where the other firm is the auditor.

What counts as a second opinion?

Paragraph 321.3 A1 describes the typical request: a second opinion on the application of tax laws and regulations, or of accounting, auditing, reporting or other standards, to specific circumstances or transactions of a company or entity that is not an existing client. The entity usually already has an accountant, auditor or adviser whose view it does not like or wants tested.

The ICAEW version of section 321 states that it does not apply to expert evidence assignments, opinions given in litigation, or opinions provided jointly to other firms and their clients. It is also different from two related situations:

  • Taking over or adding to work. If you are asked to replace an accountant, or to do work that is complementary or additional to theirs, the professional enquiry procedure in section 320 applies. See professional clearance when changing accountant.
  • Seeking a second opinion yourself. PCRT paragraph 2.14 says a member giving what they believe to be a significant opinion should consider obtaining a second opinion, with due regard to client confidentiality if it is obtained externally.

Why is a second opinion an ethical risk?

Paragraph 321.2 says giving a second opinion to an entity that is not an existing client might create a self interest or other threat to the fundamental principles. Paragraph 321.3 A1 identifies the main risk: a self interest threat to professional competence and due care where the opinion is not based on the same facts the existing accountant had, or rests on inadequate evidence. The requester controls what you see. A summary prepared to win a more favourable answer can leave out the very facts that led the existing adviser to their view.

There is also a commercial pull. A request for a second opinion is often a prelude to a change of adviser, so there is an incentive to give the answer the entity wants. The fundamental principles of objectivity and professional competence and due care both apply.

What does the code require?

R321.3 contains two firm requirements whenever you give a second opinion:

  1. confirm oral opinions in writing as soon as practicable after giving them;
  2. if asked for a general opinion on a hypothetical situation, make sure the recipient understands it was given in the context of that hypothetical situation only.

Beyond those, you apply the conceptual framework. Paragraph 321.3 A2 says the relevant factors are the circumstances of the request and all the other available facts and assumptions relevant to the judgement. Paragraph 321.3 A3 gives examples of safeguards:

  • with the client’s permission, obtaining information from the existing or predecessor accountant;
  • describing the limitations of the opinion in communications with the client;
  • giving the existing or predecessor accountant a copy of the opinion.

What if you are not allowed to speak to the existing accountant?

R321.4 requires you to decide whether you can provide the opinion at all if the entity will not let you communicate with the existing or predecessor accountant. ICAEW adds guidance in 321.4 A1: you will generally need to contact the existing accountant to understand why the consultation is being made and to have all the relevant facts. If the client will not allow this, it will generally be appropriate to decline to act, particularly where the existing accountant is the auditor.

A refusal is itself information. An entity with nothing to hide usually has little reason to stop two professionals comparing facts. Record the refusal and your reasons for accepting or declining.

Are tax second opinions treated differently?

Tax second opinions sit under both the code and PCRT. R280.24 of the code requires members undertaking any UK tax work to comply with Professional Conduct in Relation to Taxation. The version of PCRT effective from 1 January 2026 says at paragraph 2.15 that a member might be engaged to provide a second opinion on a tax planning arrangement and that PCRT applies in those circumstances. In other words, the standards on tax planning that would govern the original advice govern the second opinion too; reviewing someone else’s scheme does not lower the bar. See Professional Conduct in Relation to Taxation for those standards.

What should the engagement terms and written opinion say?

A second opinion is usually a short, discrete engagement, but it needs proper terms. The written confirmation required by R321.3 should state:

  • who the opinion is for and that it is not to be relied on by anyone else;
  • the documents and facts you were given, and that the opinion depends on them;
  • whether you spoke to the existing accountant and, if not, that you did not;
  • any hypothetical basis, stated plainly;
  • the date, since the law or standard may change.

Sending a copy to the existing accountant needs the entity’s consent under the confidentiality rules, so ask for it at the outset in the engagement letter. Because the entity becomes your client, the Money Laundering Regulations also apply: regulation 27 requires customer due diligence when you establish a business relationship.

How does this work in practice?

Illustration only. The finance director of a company you do not act for asks whether revenue on a long contract can be recognised earlier than the auditor will accept. You ask for permission to speak to the audit engagement partner and for the contract, board minutes and the auditor’s management letter. The director offers only a two page summary and refuses permission to contact the auditor. Following 321.4 A1, you decline, and you file a note recording the request, the refusal and your decision.

If instead permission is given, you speak to the auditor, review the full documents and give a written opinion that sets out the facts relied on. With the company’s consent you send the auditor a copy.

What mistakes cause problems?

  • Giving a view on the phone and never writing it down. R321.3 requires written confirmation as soon as practicable.
  • Relying on the client’s summary. The threat identified in 321.3 A1 is precisely an opinion built on different or inadequate facts.
  • Letting a hypothetical answer be used as advice on real facts. Make the hypothetical basis explicit.
  • Treating it as informal. A second opinion is professional work and needs terms and due diligence like any other engagement.
  • Ignoring a conflict. If you act for another party to the transaction, consider the conflict of interest rules before agreeing.

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Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.