What is document redaction? Definition, uses and limits

Document redaction means permanently removing information from a copy of a document before you share it. The reader sees a black bar or a blank space, and nothing is left underneath. If the text is only covered, it is not redacted. It is hidden, and hidden text can come back.

What does redaction mean?

The UK data protection authority, the ICO, defines it in guidance from July 2025: redaction is permanently removing information from a copy of a document because you cannot disclose it. Permanently: the information is gone, not covered. Copy: you never redact the original. French speakers say caviardage or occultation. German speakers say Schwärzung.

Who redacts documents, and when does the law ask for it?

Redaction lets you share a document when you may not share all of it. The logic is the same almost everywhere: release what you can, remove what you must.

• Access requests (EU and UK). Under GDPR Article 15(4), the right to a copy shall not adversely affect the rights and freedoms of others, so other people's names are often removed. The deadline is one month, extendable by two (Article 12(3)).
• Freedom of information (UK). The ICO cites information exempt under the Data Protection Act 2018 or the Freedom of Information Act.
• EU institutions (EU). Under Regulation 1049/2001, Article 4(6), if only parts of a document fall under an exception, the rest shall be released.
• FOIA requests (US). According to FOIA.gov, agencies black out information protected by one of nine exemptions and release the rest.
• US federal courts. Rule 5.2(a) of the Federal Rules of Civil Procedure limits filings to the last four digits of social-security, taxpayer and account numbers, the birth year and a minor's initials, unless the court orders otherwise.
• Everyday business: contracts for partners, files for auditors, training material.

What is the difference between cosmetic masking and true redaction?

Cosmetic masking changes what you see. True redaction changes what the file contains. A PDF can hold a text layer, comments, metadata and hidden layers. A black rectangle drawn on top touches none of them. The ICO warns that pasting such a PDF into Notepad may reveal the covered text.

How do you redact a document in six steps?

1. Work on a copy and keep the original safe. The ICO is clear: only redact from a copy, not the original.
2. Decide what goes, and why. List the categories: names, addresses, account numbers, signatures, trade secrets. Note the reason for each.
3. Find every occurrence. Search, then read every page: headers, footers, tables, stamps, handwriting, images.
4. Remove, do not cover. Use a tool that deletes the content, or flatten the pages into images. On paper, tape over or cut out, then copy.
5. Clean the hidden data: metadata, comments, tracked changes. Send a PDF, not the Word file.
6. Verify, then record. In the final file, try to select, search and copy the redacted words. Ask a colleague to check. Note who redacted what, when and why, as the ICO advises.

An example. Jane Example asks her former employer for a copy of her HR file. One email names a colleague who complained about a shared office. On a copy, the HR officer removes the colleague's name and job title, then flattens the PDF. She tries to copy text from under the bars: nothing. A colleague checks it. Then the file goes out.

What are the limits of redaction?

Redaction removes words, not context. Under GDPR Recital 26, you judge whether a person is identifiable by all the means reasonably likely to be used, such as singling out. A person can be singled out without a name. These clues often survive:

• A job title held by one person: the head of payroll in Leeds.
• A rare, dated event: the employee injured at the March trade fair.
• The length of a bar, when the reader knows the few possible names.
• Uneven work: a name removed on page 2, left in a footer on page 9.
• Other documents the reader already holds.

So a redacted document is not automatically anonymous. Labels such as [NAME1] keep the text readable, but that is pseudonymization. Under Recital 26, such data still relates to an identifiable person if extra information can link it back. Redaction lowers the risk. It does not replace your judgment.

Which tool should you use to redact?

For PDFs, use a dedicated redaction function, such as the one in Adobe Acrobat. You mark and apply redactions, then sanitize the file to remove hidden information. The result is saved to a new file. As of September 2026, Adobe offers the tool only in Acrobat Pro, Premium or Studio. Without such software, the ICO describes roundtrip redaction: convert the file to a simple image format, then back to PDF.

Be careful with online services. The Lower Saxony data protection authority calls online tools unsuitable when you must upload the original file to the cloud. It advises editing the file locally.

Tools that process the file in the browser, on your own device, are one way to follow that advice. ONYRI Sanitize, the app behind this blog, is one. It detects names, IBANs and similar items in PDFs, Word files and scans without uploading them. You review each item, and the export is flattened. Detection is not exhaustive, so step 6 still applies.

Frequently asked questions

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