How to Exclude Sensitivity-Labeled Files From Copilot Processing

Official documentation checked October 14, 2026.

To let authorized people read a document while excluding its content from supported Copilot processing, use a Microsoft Purview DLP rule that matches the document’s sensitivity label. A watermark saying “Copilot Blocked” is not an access control, and there is no documented sensitivity-label encryption checkbox named “Do not allow Copilot to read this file.”

Keep file permissions, label encryption and Copilot-specific DLP separate. The right control depends on whether you want to prevent people from reading the file or prevent an otherwise authorized Copilot interaction from processing it.

Decide Which Boundary You Need

First review who can open the file. If it is shared with too many people, correct that authorization problem through the file owner’s approved access process. A Copilot rule should not be used to disguise an over-shared library.

Sensitivity labels can classify content and apply protection or visual markings. A header, footer or watermark explains classification to a person; it does not independently make the content unavailable to AI.

For encrypted content, Microsoft documents usage-right checks for the signed-in user. Do not try to remove a supposed “Copilot account” from a permissions list or assume that encryption blocks all services regardless of the user’s rights.

Prepare an Approved Label and Test Scope

Use an existing suitable label or have the information-protection owner define one. Verify its intended meaning, publication scope and actual application to a harmless test file. Publishing a label so a user can select it is different from applying it to every file.

Check the licensing and permitted administrative roles for the DLP feature being used. The ability to create a label, configure a DLP rule, or read sensitive activity details can involve different permissions. Do not assign Global Administrator simply because an older example used it.

Choose a pilot user and a test document containing a unique, nonsensitive fact. Keep the original file’s encryption and sharing settings intact so the test measures the Copilot restriction rather than an unrelated permission change.

Configure the Label-Based Copilot DLP Rule

In Purview Data Loss Prevention, create or review a custom policy using the Microsoft 365 Copilot and Copilot Chat location. Match the intended sensitivity labels with the Content contains > Sensitivity labels condition, and use the action that prevents Copilot from processing the content. Follow the current Copilot DLP guidance for available experiences and rollout details.

This control excludes matching content from processing; it is not a request to remove the user’s normal reading permission. A matching item may still appear as a citation. Do not interpret the mere presence of a link as proof that the protected content was used in the answer.

Review the pilot scope and mode before saving. Use the documented DLP deployment process to evaluate impact, then verify enforcement in an approved enabled pilot. Simulation findings alone do not prove blocking.

Verify the Rule With Positive and Negative Tests

1. Confirm the test user can open the labeled file directly and record the actual applied label.
2. Start a fresh supported Copilot interaction and request the unique test fact from that file, without putting the fact itself into the prompt.
3. Compare with a separate approved, unrestricted test document so a general retrieval failure is not mistaken for protection.
4. Review the matching policy/rule evidence and observed behavior through the authorized Purview workflow. Keep the test timestamps and source identifiers.

An answer omitting one fact is not sufficient proof by itself. The audit schema describes Copilot interaction and resource metadata; do not search for a fabricated universal CopilotAccessBlockedByLabel operation.

Handle Exceptions Without Removing Protection

If the result differs from the expectation, check the exact label, current rule scope and mode, product support, file location and whether the answer used another source or earlier conversation context. A copied unlabeled file is a different source, not a successful test of the labeled original.

For encrypted files, consult the Purview guidance for Copilot and the actual user rights. Do not remove encryption or downgrade the label as a generic troubleshooting step.

Document any remaining unsupported scenario as a gap requiring an approved alternative control. Do not claim that one successful test blocks every upload, app, model, agent or method of copying the information.