Can your staff put client files into ChatGPT? A checklist for fiduciaries
Monday morning. Someone on your team pastes a client's tax return into ChatGPT to draft a reply faster. Twenty seconds, and it feels harmless. But where did that return just go, who can read it now, and who answers for it if the client finds out?
The short answer: only if you can say yes to three questions. Do you know which company handles the data, and in which country? Is there a contract that covers it? Do your promises to the client allow it? Accounts that staff open on their own usually fail at least one of the three.
Checked against the law on 30 September 2026
Am I at risk?
- CHF 250'000
The highest fine in the Data Protection Act for disclosing secret client data, or for handing data to a provider without the required safeguards. It is personal: as a rule it is imposed on the person responsible, not on the firm, when the breach is intentional.
- The boss too
If a team member commits such a breach, whoever runs the firm can face the same penalty for failing in their duty to prevent it, even through negligence (art. 64 FADP and art. 6 of the Administrative Criminal Law Act).
- US law
US providers can be required to hand data they control to US authorities, even when it is stored in Switzerland (CLOUD Act).
The checklist
0 of 10 checked
Ask the team, look at browser extensions and phone apps, and check expense claims for subscriptions. The tool you don't know about is the one you can't control.
Client emails, tax returns, payslips, bank statements. Names, AHV numbers, salaries and balances are all personal data.
A free or personal account runs on consumer terms. A business plan comes with a different contract. Which one is your team really using?
Some consumer plans may use conversations to train their models, and keep them for a while, unless a setting is off. Read the terms of the plan in use, not the homepage.
A company that handles client data for you is what the law calls a processor. That's allowed with a contract, if it only does what you could do yourself and keeps the data secure (art. 9 FADP). Check whether the terms of the plan you actually use meet those conditions, including processing limits, confidentiality and security: neither a consumer nor a business label settles it.
Many AI tools process data in the United States. Sending client data there needs a legal basis, for example Swiss-US Data Privacy Framework certification or standard data protection clauses (arts. 16 and 17 FADP).
Some engagement letters rule out passing data to third parties, or allow only named subcontractors. An AI provider is a third party. If your contract with the client says no, the law says no too (art. 9 FADP).
Replace names, AHV numbers, IBANs and addresses when you can. It lowers the risk, but details can still point to a client, so it doesn't replace the other checks.
Which tools, for which tasks, with which data, and what never goes in. A page people can find is a page they can follow.
People paste client files to save time, not to cause harm. Explain the rules, repeat them for every newcomer, and give them a tool they're allowed to use.
Ticked them all? Rules that exist only in your head don't stop anyone. The next step is to write them down for your team: the kit has a one-page policy to adapt. Get the kit
Which tasks can go where?
The kit sorts six everyday tasks. Two of them:
- Rewording a general letter or email with no client details
- A public tool is fine.
- Explaining a tax rule or a new ordinance in general terms
- A public tool, then check the official source.
- Summarising a client's email or letter
- In the kit
- Drafting a reply that quotes figures from the client file
- In the kit
- Reading payslips, bank statements or tax returns
- In the kit
- Anything on health, social assistance or proceedings
- In the kit
Why fiduciaries are more exposed
A fiduciary sees income, wealth, family situations and tax matters: often the most private numbers in a client's life. The Data Protection Act fines anyone who intentionally discloses secret personal data they learned through work that requires knowing it, up to CHF 250,000 (art. 62). Handing data to a provider without the conditions of article 9 paragraphs 1 and 2, or sending it abroad without the protection of article 16 and outside the exceptions of article 17, can be fined too (art. 61). Both are prosecuted only if someone files a complaint. When the breach is a team member's, whoever runs the firm can face the same penalty for failing in their duty to prevent it, even through negligence (art. 64 FADP, art. 6 ACLA). If your firm also acts as an auditor bound to secrecy under the Code of Obligations, the Criminal Code's professional secrecy covers that work, including the staff who assist (art. 321); other checks of accounts are not covered by it.
Some data needs even more care
Data about health, social assistance, or administrative and criminal proceedings is sensitive personal data under the law (art. 5 FADP). It turns up in fiduciary files more often than it seems: a medical expense deduction, a disability pension, a tax penalty.
What works in practice
A common setup has three tiers: a public AI tool for work without client data, a business account under contract for the client work your contracts allow, and a private AI run in Switzerland for anything confidential. Where each line falls depends on your clients and your engagement letters.
Where does your firm stand?
The self-check takes two minutes and says which first step fits. Or talk it through in a free 15-minute call.
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Your situation
What AI should do for you, and what it must never see.
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The next step
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