How to redact a confidential business document
To redact a confidential business document is to remove or replace, before it is passed on, the information that identifies people or falls under business secrecy: names, contact details, identification numbers, amounts, case references. The document keeps its structure and meaning; only the sensitive data disappear or take the form of an alias.
Business documents travel well beyond the department that produced them. An employment contract goes to the lawyer during a labor dispute. A balance sheet is sent to a bank, a buyer or a consultant. A patient file serves as a case study in a multidisciplinary meeting. A tax notice accompanies a rental or loan application. A customer tracking spreadsheet is handed to a contractor for analysis. At each step, the recipient needs only part of the content.
Two sets of rules apply. The GDPR protects personal data and requires you to limit what you pass on to what is strictly necessary. The EU Trade Secrets Directive (EU) 2016/943, transposed in France by the law of 30 July 2018, protects business secrets: prices, margins, customer lists, know-how. Regulated professions add their own professional secrecy. Redacting a business document lets you respect all three frameworks without giving up sharing the file.
The approach rests on three decisions: identify precisely what must be removed, choose how to remove it according to the recipient, then check that nothing remains in the final file. Each of these decisions is detailed below, with examples drawn from everyday documents.
Redact a business document: spot the data to remove
Direct identifiers are easy to spot: surname, first name, email, phone number, address. The riskiest are numbers, because they identify a person uniquely: the French social security number (NIR, 15 digits including the key), tax number, IBAN, French company numbers (SIREN and SIRET), case or contract number. They are also the easiest to detect automatically, because they follow precise formats, often with a check digit. The table below lists the data to watch in five common documents.
| Document | Data to redact first |
|---|---|
| Employment contract | Name, address, date of birth, social security number, employee ID, pay |
| Balance sheet and notes | Company name, company number, directors, customers and suppliers named |
| Patient file | Identity, social security number, date of birth, attending physician, admission number |
| Tax notice | Tax number, notice reference, address, reference taxable income |
| Commercial contract | Parties, signatories, IBAN, prices and negotiated terms |
Indirect identifiers need more attention. A unique role ("the finance director"), a hiring date, a small town or a dated event is sometimes enough to recognize someone. Health data mentioned in a patient file also fall under article 9 of the GDPR, which strictly limits their processing.
Finally, think of the areas people forget: headers and footers, scanned signatures, stamps, comments, hidden cells in a spreadsheet, the file name and the document properties. A well-redacted business document is redacted in every layer, visible and invisible, not just in the body text you reread on screen.
Choose the right mode: black out, mask or pseudonymize
There are three ways to redact a piece of information, and the right choice depends on the recipient and the intended use.
- Black out: the data is replaced by a black bar. This is the expected result for a document filed in court, a published document or a reply to an access request. Readers see that information was removed, without being able to read it.
- Mask: the data is replaced by a generic label, such as [PERSONNE] or [IBAN]. The text reads smoothly and the type of information stays clear.
- Pseudonymize: each value receives a stable alias, such as PERSONNE_001 or SOCIETE_002. The same name always becomes the same alias, which preserves the logic of the document: you know who writes to whom, who signed what.
Pseudonymization is the most useful mode when the document still has to be analyzed, by an expert or by an AI assistant. It is defined in article 4 of the GDPR: the information that leads back to people is kept separately. With a mapping table, you restore the real names in the answer you receive; the pseudonymized document nevertheless remains subject to the GDPR.
Blacking out and masking are permanent, provided the original text is really deleted. They suit anything that will be widely shared or kept for a long time outside your control. One document can combine modes: names pseudonymized for readability, IBAN and social security number masked because they add nothing to the analysis.
Redact without leaks: checks and offline processing
The first question is where the processing happens. Sending a confidential document to an online service to have it redacted means handing it in clear to a third party before it is protected. If you choose that route, the provider acts as a processor within the meaning of article 28 of the GDPR, and a contract must set out its obligations. For a file covered by professional secrecy, processing on your own computer removes that step.
Before sending, five quick checks prevent most incidents:
- select and copy the blacked-out text, then paste it elsewhere: nothing should reappear;
- open the file properties: author, company and title must reveal nothing;
- check comments and tracked changes;
- reread headers, footers and cover pages;
- rename the file if it contains the name of a customer or employee.
Biffer, the software we publish, applies these principles on Mac and PC with no connection at all during processing. It recognizes common data and the fields of 18 professions, from the French health professional number (RPPS) to the insurance claim number, lets you validate each detection in a preview, then rewrites the Word, Excel or PDF file and clears its metadata. A right-click on a file, then "Biffer", is enough to start, and your settings are saved as reusable configurations. The page offline software explains this local operation, and the page pricing presents the two plans.
Your business documents redacted in minutes, on your own computer
Biffer, published by Opcadia and designed by Romain Rissoan, detects the sensitive data in your contracts, balance sheets and files without sending anything over the internet. 5 files per month are free, with every feature.
Frequently asked questions
Should I redact a document I send to my lawyer or accountant?
These professionals are bound by secrecy, and you can send them a complete file when they need it. Redaction remains useful for what goes beyond their engagement: data about third parties unrelated to the matter, documents later shared with a colleague, an expert or an AI tool.
Is black highlighting in Word enough?
No. Highlighting or a black shape placed over the text leaves it in the file: copying it or changing the color is enough to read it. The text itself has to be replaced, then the metadata and revision history cleared.
Can the original data be recovered after redaction?
Only if you chose pseudonymization with a mapping table. Biffer encrypts this table and keeps it on your computer, so you can restore the names in a document returned by a third party or an AI. Without a table, redaction is permanent.
Your business documents anonymized, ready to be published or handed to an AI tool.
Biffer runs on your computer without sending a single file. Free for five files a month, unlimited for €10 excl. VAT per computer.
100% offline · Free: 5 files a month · No file sent