How to mark a confidential document
A confidential document is one whose circulation is deliberately limited to designated people, because its disclosure would harm the organization, its clients or the people it mentions. Marking it as confidential means flagging it visibly and consistently, with a label, a classification level and distribution rules known to all its readers.
The label does not protect the content by itself: a document marked "Confidential" can be copied, forwarded and printed like any other. It nonetheless serves three useful purposes. It warns the reader and binds them, especially when a non-disclosure agreement or internal rules refer to it. It organizes circulation: everyone knows to whom the document may be passed. Finally, it serves as evidence: to be protected as a trade secret under the EU Trade Secrets Directive (EU) 2016/943, information must have been subject to "reasonable steps under the circumstances" by its holder to keep it secret (article 2), a rule that French law reproduces in article L151-1 of the Commercial Code, and marking is one of those steps.
In our training and consulting work, we often see sensitive documents with no label at all, and harmless files stamped "strictly confidential", which cheapens the label.
This article gives the standard labels, presents the confidentiality levels used in business and government, then explains how to apply them in Word. To remove sensitive information from a document before passing it on, the article how to redact a confidential business document describes the method.
Standard labels for a confidential document
An effective label is short, visible on every page and consistent from one document to the next. Here are the most widespread wordings:
- "Confidential": distribution limited to the designated recipients and to those who need to know;
- "Strictly confidential": named distribution, no forwarding or copying without the sender's consent;
- "Internal use only": document reserved for the organization's employees;
- "Confidential, do not distribute": an explicit wording, useful for a document that might be forwarded by mistake;
- "Private and confidential": on an envelope or a letter, to be opened by the addressee only.
For an email, the label goes in the subject line ("[Confidential]") and can be supplemented by a notice at the bottom of the message, for example:
This message and its attachments are confidential and intended solely for their addressees. If you have received it in error, please notify the sender and delete it.
Placement matters as much as wording. The label appears in the header or footer of every page, on the cover page and, if possible, in the file name. For a highly sensitive document, add the list of recipients, the date, the version number and the copy number: if there is a leak, you will know which copy circulated. Finally, a written distribution rule, even a short one, gives these labels a meaning the whole team shares.
Confidentiality levels in business and government
No law imposes a confidentiality scale on businesses. Most adopt three to five levels, often along the lines of the model below. What matters is that each level matches a simple distribution rule that anyone can apply without asking a manager.
| Level | Example documents | Distribution rule |
|---|---|---|
| Public | Brochure, job offer, press release | Unrestricted |
| Internal | Procedures, org chart, internal memos | Employees and contractors under contract |
| Confidential | Client contracts, payroll files, HR files, budgets | People who need to know |
| Strictly confidential | Acquisition project, results before publication, litigation | Named list, numbered copies |
The ISO/IEC 27001 standard, in its 2022 version, requires information to be classified according to its sensitivity (control 5.12) and labeled accordingly (control 5.13), without setting the names of the levels: each organization defines its own. Classification is the job of the information owner, who reviews it when sensitivity changes, for example after results are published or a contract is signed.
Governments have their own classification systems for national security information. In France, since 1 July 2021, there are only two levels, "Secret" and "Très Secret" (Top Secret), defined by the Defense Code and detailed in interministerial instruction No. 1300; the marking "Diffusion restreinte" (restricted distribution) is a protective marking, not a classification level. These markings are reserved for information concerning national defense and security. For its own documents, a business uses distinct labels, such as those in the table above, to avoid any confusion.
Mark a Word document and protect its content
Word offers several ways to show that a document is confidential, to be combined according to the level chosen:
- The watermark: Design tab, Watermark. Word offers predefined watermarks, including "CONFIDENTIAL", and accepts custom text.
- The header or footer: Insert tab, Header or Footer. The label is repeated automatically on every page.
- Sensitivity labels: if your organization has configured them in Microsoft 365, they mark the document and can apply encryption.
- The password: File, Info, Protect Document, Encrypt with Password. The content becomes unreadable without the password.
These measures flag and lock, but they travel with the document: any recipient who opens it, with the password if there is one, reads the full text. When a confidential document has to leave its circle (lawyer, expert, contractor, AI assistant), the safest protection is to remove the information the recipient does not need. The risks specific to assistants are detailed in the article ChatGPT privacy.
Biffer, the software we publish, does this on your computer, with no connection: it detects names, contact details, numbers and profession-specific fields, replaces them with aliases or masks, clears the metadata and keeps, if you wish, an encrypted table to restore the values. The page redact a document details the approach, the page offline software explains why local processing matters, and the page pricing presents the plans.
Share your confidential documents without what must stay with you
Biffer, published by Opcadia and designed by Romain Rissoan, trainer and consultant, runs on Mac and PC, entirely offline. The free plan covers 5 files per month; unlimited use costs €10 excl. VAT (€12 incl. VAT) per computer, paid once.
Frequently asked questions
What are the confidentiality levels?
In business, no scale is imposed; the most common has four levels: public, internal, confidential and strictly confidential. Governments use their own classification for national security; in France, it has had two levels since 2021, "Secret" and "Très Secret", reserved for information concerning national defense.
How do I put "confidential" on a Word document?
The simplest way is the watermark: Design tab, Watermark, then the "CONFIDENTIAL" template or custom text. Add the label in the header or footer so that it appears on every page, and encrypt the file with a password if its content requires it.
Does the "confidential" label have legal value?
It is not enough to make information secret, but it counts. It reminds the reader of the confidentiality commitment that refers to it, and it is one of the reasonable steps required by the EU Trade Secrets Directive, and by article L151-1 of the French Commercial Code, to claim trade secret protection.
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