AI tools are only as safe as what you type into them. Most data mistakes aren’t malicious. Someone pastes a customer email thread in to “tidy it up”, or drops a payroll export in to “find the errors”. This guide sets out what should never go into a public AI tool, and how to anonymise your work in under a minute so you can still get the help you need.
Why it matters
When you paste something into an AI chat tool, it leaves your control. Depending on the tool, your plan and your account settings, what you type may be stored, reviewed by the provider or used to improve the service. You also remain responsible for any personal data you share: UK GDPR obligations don’t pause because the processing happened in a chat window.
None of this means you should avoid AI. It means you need a simple, consistent habit before you paste. We call it the Data Red-List.
The Data Red-List: four things that never go in
| Category | Examples | What to do instead |
|---|---|---|
| Financial & payroll | Salaries, bank details, profit margins, tax references | Anonymise the figures or use realistic stand-in numbers |
| Credentials & access | Passwords, API keys, network paths, database logins | Remove completely. Never paste them, not even “just to check the format” |
| Personal data | Customer names, home addresses, phone numbers, health information | Replace with placeholders such as [Client_A] or [Employee_3] |
| Confidential information | Unannounced products, trade secrets, client lists, contract terms | Only use tools your organisation has approved for confidential work |
How to anonymise in 60 seconds
Most tasks don’t need the real details at all. AI is helping with the structure, tone or logic, not the names and numbers. Before you paste:
- Swap names for placeholders. “Sarah at Brightwell Ltd” becomes “[Contact_A] at [Client_A]”. Use the same placeholder every time a name appears so the meaning stays intact.
- Change or round the numbers. If you need help with a formula or a variance explanation, scale the figures or use made-up values with the same shape.
- Strip the identifiers. Email signatures, addresses, account and order numbers, and anything in a footer.
- Keep the key offline. Note which placeholder means what in your own document, then swap the real details back into the finished draft yourself.
Before and after
Before: “Draft a reply to James Okafor (james.okafor@…) about invoice #48213 for £12,450, which is 40 days overdue.”
After: “Draft a polite but firm reply to [Customer_A] about an invoice that is 40 days overdue. Keep it under 120 words and offer a short call to agree a payment date.”
The second version gives the AI everything it needs to write a good email, and nothing it doesn’t.
Public tools vs approved tools
Business and enterprise versions of AI tools usually come with stronger data controls than free personal accounts, such as limits on how your data is used and admin oversight. But “we pay for it” isn’t the same as “it’s approved for everything”. The safest rule is simple: use the tools your organisation has approved, for the kinds of data it has approved them for. If nobody has told you what’s approved, that’s a question worth asking this week.
A five-second check before you paste
- Is there a real person’s name, contact detail or personal information in this?
- Are there real financial figures I haven’t changed?
- Is there a password, key or login anywhere, including in a screenshot?
- Would I be comfortable if this text were read by someone outside the company?
- Is this tool approved for this kind of information?
If any answer gives you pause, anonymise first. It takes a minute, and it means you can use AI confidently every day instead of nervously now and then.
