Does Microsoft Copilot Train on Your Company Data?

No. Microsoft states that your prompts, responses and tenant data are never used to train its foundation models. That is the question everyone asks, it has a good answer, and it is not the risk that actually bites teams. The real one is permissions.

This question kills more rollouts than any other, usually in a meeting where nobody has the documentation open.

The direct answer

Microsoft's enterprise data protection documentation states that prompts, responses and data accessed through Microsoft Graph are not used to train the foundation models behind Microsoft 365 Copilot, and that the data stays inside your Microsoft 365 compliance boundary.

So you can answer the question in the meeting and move on. It is worth knowing that the commitment attaches to the licensed enterprise product, which matters for a reason I will come back to.

The risk that is actually there

Copilot does not need to leak anything to cause a problem. It only needs to be helpful about a file that was already shared too widely.

Someone asks a completely reasonable question. Copilot searches what that person already has permission to see, finds a spreadsheet on a site that was opened up to the whole company two years ago for one project, and answers accurately. Nothing was breached. The permission was always wrong, and Copilot is the first thing that ever went looking.

What to do before a wide rollout

• Review the over-shared sites. Anything set to everyone in the organisation, especially old project sites nobody owns any more.
• Apply sensitivity labels to what actually matters, rather than to everything, which people learn to ignore.
• Start with a pilot group whose permissions you have actually looked at, not the whole company at once.
• Tell people what it can see. Most staff assume it is searching the internet. It is searching them.

Why the answer depends on which Copilot

The enterprise commitment covers the licensed Microsoft 365 product. The consumer version is a different product with different terms, and plenty of employees are signed into it with a personal account on a work laptop.

If your policy says Copilot is approved, be specific about which one. That gap is the subject of its own entry.