ChatGPT for UK accountants without exposing client details

AI for accountants rarely starts with the partner. It is the trainee tidying a client’s email, the payroll clerk asking why a starter’s tax code looks wrong, the senior drafting a letter to HMRC from the notes on file.

Each piece is short, and each carries enough at the top to say exactly whose affairs these are: the Unique Taxpayer Reference, the National Insurance number, the date of birth, the company number and the VAT registration number, often with a bank detail or two alongside and a passport copy on file. Since 1 July 2026 the ICAEW Code of Ethics has placed the responsibility for that on you, through R114.1(d): reasonable steps so that personnel under your control keep your duty of confidentiality.

The work itself follows the calendar. In January it is Self Assessment queries and payments on account. Around a company’s year end it is the notes behind a CT600 and the disallowable items a director wants explained. Every month there is a VAT return that does not reconcile, an RTI submission that disagrees with the payroll, and in the summer the benefits on a P11D. The text changes; the header with the client’s references does not.

So the question is less which assistant the firm licenses than what the junior’s text still says when it arrives. A step taken on the machine where the pasting happens is one you can point to.

Accountants can use ChatGPT on client work as long as the client’s details are out of the text first. In the made-up query below, the client’s name, date of birth and UTR become placeholders on the junior’s own machine, and the question about the buy-to-let flat reaches the assistant as written.

That is all the assistant needs to explain whether the gain falls in this year’s return and what the client should send. When the reply comes back, the real name and UTR go back into it on the same screen.

Payroll is the other place it earns its keep. In a made-up RTI query, the employee’s name and NI number, the employer PAYE reference, the Accounts Office reference and the VAT registration number all became placeholders, which leaves the question about an emergency tax code readable and the employer unnamed.

With AI in accounting, the word in R114.1(d) that matters is personnel, which is why it is quoted here in full: you answer for the trainees and clerks under you, not just your own keyboard.

In most firms they are the quickest to try a new tool, so a step that works on each of their machines is one you can name when asked what the firm actually did.

On 28 July 2026 ICAEW’s regulatory policy director applied that duty to AI in a note to firms. It asks for due diligence, contractual protections and internal approval before confidential client information goes into a system. A paid plan with the AI provider is the contractual part; it is not the due diligence, and it is certainly not the approval, which remains your firm’s own policy. What you tell clients belongs in an AI clause for the engagement letter.

The same note asks firms to understand where data is stored, who can access it and whether it may be used to train models. Whatever Nonimo swapped out was never sent, so the provider holds nothing of it. For what OpenAI keeps of the rest, read how ChatGPT treats a UK user’s data.

HMRC’s Standard for Agents, last updated on 9 February 2026, is explicit about what it does not cover. It adopts three of the five fundamental principles in the Professional Conduct in Relation to Taxation and says plainly that objectivity and confidentiality are not specifically covered. So the confidentiality rule that applies to a junior pasting a client query is ICAEW’s, ACCA’s or the CIOT’s, not HMRC’s.

What HMRC does ask is practical. Agents keep client information secure, comply with the UK GDPR and the Data Protection Act 2018, and never ask a client to share their sign-in details for HMRC online services. That last rule earns a mention here because sign-in details turn up in client emails more often than anyone admits, and a forwarded email is exactly what ends up in a chat window.

The money laundering file is the other thing to keep apart. Under the Money Laundering Regulations 2017, an accountancy service provider keeps its due diligence records, passport copies included, for five years after the relationship ends, then deletes the personal data. None of that file needs to pass through an assistant, and a summary of it can go through with the client’s name and passport number as placeholders.

Most practices start where queries are pasted every day, the payroll desk or the Self Assessment team, on one Mac or Windows PC.

The tax team, the bookkeepers and the client inbox can follow, one desk at a time, before the January peak rather than during it.

When the whole practice should be covered at once, IT installs the browser extension through policy, and it covers text going into ChatGPT, Claude or Copilot without anyone pressing a key; hello@nonimo.ai sets that up. Staff carry on in the browser they already use.