Accountancy practice records and AI training: a UK guide

Accountancy practices hold years of detailed financial work: workpapers, reconciliations, accounts, tax computations, financial models and the correspondence around them. AI developers training systems to do financial work want exactly this kind of record. But most of it is client information, and the profession's rules on confidentiality are strict.

This guide explains what a UK practice can and cannot license, and how client authorisation works under the ICAEW and ACCA codes. It covers firms registered under SIC codes 69201 (accounting and auditing), 69202 (bookkeeping) and 69203 (tax consultancy) (Companies House). For the basics, start with our UK guide to selling company data to AI developers.

What accountancy practices hold

• Client work. Workpapers, reconciliations, accounts, tax computations and returns, financial models and management reports. More of it now sits in software. From 6 April 2026, Making Tax Digital for Income Tax applies to sole traders and landlords with income from self-employment and property over £50,000, and they or their agent "will need to use software that works with Making Tax Digital for Income Tax" (GOV.UK).
• Anti-money laundering files. External accountants and tax advisers are in scope of the Money Laundering Regulations 2017 (reg 8), which defines both terms in reg 11. They must keep copies of customer due diligence documents for five years after the business relationship ends (reg 40).
• Payroll records. Employers must keep payroll records "for 3 years from the end of the tax year they relate to", including "employee leave and sickness absences" (GOV.UK). Practices that run payroll for clients hold these too.
• Practice records. Procedures, checklists, templates, internal training, practice management, time and billing, and email.

Ownership is not the main question

Who owns a file matters less than who it is about. An older ACCA factsheet says ownership depends on the work. "Where the work is to prepare accounting records for a client, the records belong to the client." For tax compliance work, "the entire tax file will often be deemed to belong to the client". For advice work, "Drafts, internal memoranda and similar documents in connection with that work belong to the member" (ACCA). But owning a working paper does not free you to use what it says.

The ICAEW Code of Ethics applies from 1 July 2026. Paragraph 114.0 A1 says "A safe and proper approach" is to "assume that all unpublished information about a client's or employer's affairs, however gained, is confidential". Under R114.2, an accountant must not:

• disclose confidential information gained in professional and business relationships
• use it "for the advantage of the accountant, the firm, the employing organisation or a third party"
• use or disclose it after the relationship has ended.

(ICAEW)

Licensing client information to an AI developer for a fee is a use for the firm's advantage. ACCA adopts the international IESBA Code in full, with the same rules (ACCA).

When client authorisation makes it possible

R114.3 allows use or disclosure where "This is authorised by the client or any person with the authority to permit disclosure or use of the confidential information and this is not prohibited by law or regulation."

The guidance that follows, paragraph 114.3 A3, covers uses like this. A firm can seek a client's authorisation "where the information is to be used for training purposes, in the development of products or technology, in research or as source material for industry or other benchmarking data or studies". The points to tell the client, "preferably in writing", can include:

• the nature of the information
• the purpose
• who will carry out the activity
• "Whether the identity of the individual or entity that provided such information or any individuals or entities to which such information relates will be identifiable from the output".

(ICAEW)

The tax professional bodies take the same line on AI. Their January 2026 guidance, issued by AAT, ACCA, ATT, CIOT, ICAEW, ICAS and STEP, says "Members may only disclose information to third parties with proper and specific authority from clients" (PCRT AI guidance). So make any authorisation specific: name the purpose, the kind of buyer, and how identities will be protected. A general clause in an engagement letter may not be enough. A CCAB case study on using client data to train AI advises asking existing clients to opt in, "rather than assuming implied consent" (CCAB).

What must stay out

• Anti-money laundering records. They "may only be processed for the purposes of preventing money laundering, terrorist financing or proliferation financing", and "No other use may be made" of them, with narrow exceptions (reg 41). They must also be deleted at the end of the retention period, with some exceptions (reg 40). Leave them out.
• Client information without authorisation. Everything in client files, including names, figures and correspondence with HMRC.
• Payroll and HR data. Sickness records are data concerning health, which is special category data under the UK GDPR (Article 9).
• Identifiable detail. Removing a name is not enough. The PCRT guidance warns: "Even if a client/business name is not disclosed to the public AI tool, it may be able to identify them" (PCRT AI guidance).

What a practice can license

• Without client authorisation: your practice's own know-how and operating records, once all client information is removed. That means procedures, checklists, templates, internal training, and how the practice runs.
• With specific written authorisation: client files, de-identified so that no one can be identified from them. Our glossary explains the motivated intruder test that the ICO uses to judge this.

What buyers want

• Mode sets a minimum of "10+ for accounting, finance, and medical" firms, one of the lowest it publishes, although it says teams based mainly in the US fit best (Mode).
• Labelbox Prism lists "Financial reasoning traces" as an urgent category (Prism).
• Handshake AI names QuickBooks and NetSuite among its sources, and Grepped connects to QuickBooks and Xero.
• Pewter, a US firm that runs data-licensing deals for owners of US firms, says "A 60-person accounting firm was paid $350,000". Its licensing partner published that deal. Pewter also lists an accounting group deal at $280,000, published by another licensing firm. The records it describes include "Five years of workpapers, reconciliations, financial models and tax-preparation files". Pewter says these are "the publishers' own statements, not independently verified", and that it did not advise on them (Pewter).

Those US records are client workpapers. A UK practice would need each client's specific authorisation to license material like that.

If the practice is closing or being sold

Professional, scientific and technical activities, which include accountancy, had 1,913 company insolvencies in England and Wales in the 12 months to August 2026 (Insolvency Service). There is no figure for accountancy alone.

Closing or selling a practice does not free client information. The duty of confidentiality continues after the client relationship ends (R114.2). License only what your practice may use: its own know-how and operating records, or client files with specific authorisation.

Before you talk to buyers

1. Separate client work from practice records. Most of the value is in client work, and so are most of the restrictions.
2. Ring-fence your AML files. Keep them out of scope entirely.
3. Remove payroll and HR data. Sickness records are health data.
4. Decide on authorisation. If you ask clients, cover every point in paragraph 114.3 A3, in writing.
5. De-identify with care. Removing names is not enough.
6. Check your professional body's guidance. Record your decision and your reasons.

Tydex helps practices work out what they can license, and brings written offers from buyers. Get a free valuation.