A Classification You Will Actually Use

'Never put company data into AI tools' fails for a predictable reason: it is unenforceable, obviously over-broad, and the moment someone breaks it once with no consequence, the whole policy stops meaning anything.

What works is a small number of tiers people can hold in their head while working.

Four tiers

• Green — already public. Your website copy, published material, public documentation, generic questions. Any tool, any plan, no thought required
• Amber — internal but not sensitive. Draft copy, internal process notes, anonymised examples, meeting notes with no names. Approved tools on a business plan
• Red — confidential or personal. Customer records, employee data, financials, contracts, unreleased plans, anything under NDA. Only tools with a signed agreement, and only where there is a real business need
• Black — never, on any tool. Passwords, API keys, tokens, payment card data, health records, government identity numbers, anything covered by a specific legal regime

Redaction is the skill that unlocks the rest

Most red-tier work becomes amber with two minutes of substitution, and the answer you get back is just as useful — models reason about structure, not about whether the name is real.

Instead of:
"Rewrite this reply to Sunita Shrestha at Everest Trading,
who is angry that invoice INV-2024-8871 for NPR 340,000
is three weeks late."

Send:
"Rewrite this reply to a long-standing B2B client who is
angry that a mid-value invoice is three weeks overdue.
Tone: apologetic but not grovelling, with a specific
commitment to a date."

Then put the real names, numbers and dates back yourself.

Redaction rules that hold up

• Replace names with roles — 'the client', 'the account manager', 'a supplier'
• Replace figures with magnitude — 'a mid-value invoice', 'roughly a quarter of annual revenue'
• Strip identifiers entirely: account numbers, invoice numbers, emails, phone numbers, addresses, national IDs
• Watch for the combination problem. Employer plus role plus city plus start date identifies one person even with the name removed
• Do the substitution before pasting, not after. 'I will clean it up next time' is how every one of these incidents starts

Screenshots and files count

Uploading a spreadsheet, a PDF or a screenshot is the same act as pasting its contents, and it is where people are least careful — a screenshot of a dashboard usually includes a sidebar, a customer name and an email address nobody thought about.

Crop before uploading. For spreadsheets, delete the columns that are not part of the question rather than uploading the whole export.