Redline vs Blackline: What's the Difference in Contract Negotiation?

What is the difference between a redline and a blackline?

A redline is a working draft of a contract in which one party proposes edits as tracked changes: deletions struck through, insertions underlined, each change attributed to its author and open to acceptance or rejection. A blackline is a comparison report that software generates from two separately saved versions of a contract, showing only the net differences between them in a single marked-up view. Put simply, the redline is how you negotiate and the blackline is how you verify what actually changed.

The two words are often used interchangeably, and plenty of lawyers say "send me a redline" when they mean a comparison. That looseness is harmless most of the time. It stops being harmless when a counterparty sends back a clean document and says "we've accepted most of your points," because only one of these two documents can tell you whether that is true.

This guide is written for in-house legal teams and the commercial colleagues who negotiate alongside them. It covers what each document is, where the terms come from, when to use which in a negotiation round, how to produce a blackline in Microsoft Word, and a worked example of the kind of silent change that only a blackline catches.

Redline and blackline at a glance

The distinction that matters is in the "what it shows" row. A redline is only as complete as the person who made it. A blackline does not depend on anyone's discipline, because it is computed from the files themselves.

What is a redline?

A redline is a version of a contract that shows proposed changes against the previous draft. In modern practice it is a Word document with Track Changes switched on. Microsoft's own guidance describes the convention: with tracking on, deletions are marked with a strikethrough and additions with an underline, and different authors' changes appear in different colors. Comments sit in the margin alongside the edits, explaining why a change is proposed.

A redline is a conversation. When you send one, you are saying "these are the changes we want, and here is why." When the other side replies, they accept some edits, reject others, and add their own, so a single redline can accumulate several rounds of marks from several people.

That accumulation is also its weakness. A redline shows only what was tracked. If someone switches Track Changes off, pastes in a clause from another agreement, or accepts their own edits before sending, the result can look like a clean, tidy draft while carrying changes nobody flagged.

For the mechanics of producing a good redline in Word (tracking settings, comments, author names, and hygiene before you send), see our step-by-step guide on how to redline a Word document.

What is a blackline?

A blackline is a comparison. You take two versions of a contract, an original and a revised one, and software produces a third document in which every difference between them is marked up as if it had been tracked. Wikipedia's entry on document comparison describes this as "blacklining": a computer process to identify changes between documents.

Microsoft Word has the feature built in, and names it after the legal use case: Compare two versions of a document (legal blackline). Two details in Microsoft's documentation matter for negotiation work:

• By default the result opens in a new document, and the two source documents are not changed. You keep your version and theirs intact and get a separate report.
• Existing tracked changes are accepted before comparing. If either version contains tracked changes, Word asks you to accept them. Tracked changes in the original are accepted, and the differences in the revised version are shown as tracked changes. The blackline therefore compares the documents as they would read if every pending edit went through.

A blackline is an audit. It does not care whether the other side was careful, honest, or in a hurry. It shows what is different.

Where the terms come from

Both names predate word processors. Reviewers compared printed drafts by hand, using a ruler and a red pen to strike through deleted text and underline inserted text; when the marked page went through a photocopier, the copies came out black. That is the origin story recorded in the document comparison entry, and it explains why the two words drifted into describing the same kind of document.

Is "blackline" British and "redline" American?

You will see that claim online, but there is no reliable rule. Usage varies by firm, by practice area, and by where people trained, and many lawyers in every market use "redline" for both documents. Treat the words as loose labels and describe the document you mean: "a comparison of your draft of 12 May against ours of 3 May" is unambiguous in any jurisdiction.

When to use each in a negotiation round

A typical bilateral negotiation runs in rounds, and each document has a natural place in the round.

Use a redline when you are proposing. Every time your side changes the contract, send the changes as tracked edits with short comments explaining the important ones. A redline invites a response on each point and keeps the reasoning attached to the text.

Use a blackline when you are receiving. Every time a version comes back, compare it against the last version you sent, not against the original template and not against their previous draft. That comparison is the only way to see the full set of changes since your last position.

Use a blackline before signature. Compare the execution copy against the last draft both sides agreed. It confirms that the document going out for signature says exactly what was negotiated, with nothing added, lost or reverted in the final tidy-up.

Use a cumulative blackline when you are closing. Before signature, compare the execution version against your starting template or first draft. The cumulative view shows the business owner and approvers what the deal moved from, in one document, rather than making them reconstruct it from six rounds of redlines.

Send a blackline to the other side when you want to prove good faith. When you return a clean version, attach a comparison against their last draft. It saves them time, and it removes any suspicion that something was changed quietly.

Why you should blackline every clean return

The most common failure in contract negotiation is not a bad clause. It is an unnoticed one. A counterparty returns a document that looks clean and says the changes were minor, and nobody checks.

There are several innocent ways this happens, and one that is not:

• Tracking was off. Someone edited a passage before switching Track Changes on, or turned it off to fix formatting and forgot to turn it back on.
• Changes were accepted before sending. The other side accepted their own edits to "tidy up," so their changes now look like original text.
• A clause was replaced wholesale. A section was pasted in from their own template, and the tracked view shows it as one block rather than highlighting the substantive differences inside it.
• The wrong base version was used. They edited a draft from two rounds ago, silently undoing points you had already agreed.
• Someone changed something and hoped you would not notice. Rare, but the blackline treats it exactly like the innocent cases.

In every case the fix is the same: compare their return against the last version you sent. It takes a minute and turns "we trust they flagged everything" into "we know what changed."

Worked example: the silent change a blackline catches

Consider a supply agreement in its third round. Your side sent version 3 with two tracked edits: a shorter payment term and a tighter definition of "Confidential Information." The supplier returns version 4 as a clean document with a covering email:

"We've accepted your change to the confidentiality definition and made a small counter on payment terms. Clean version attached."

The email is accurate as far as it goes. The blackline of version 4 against version 3 shows three differences, not two:

Two words disappeared from clause 11.1: "or payable." Read quickly, the clause looks identical. In substance it can lower the liability cap, especially early in the contract term when little has actually been paid: a claim in month two is capped at two months of paid fees rather than the fees due over the year. Nothing in the clean document signals the change, and nothing in the email mentions it.

Without the comparison, the change would most likely have survived to signature. With it, your response in version 5 is straightforward: accept or counter the payment term, and restore "or payable" with a comment asking the supplier to confirm the deletion was unintended. For what a standard cap looks like and how to negotiate it, see our guide to limitation of liability clauses.

How to create a blackline in Microsoft Word

Word's legal blackline feature is available in the desktop app. Microsoft documents the steps on its legal blackline support page:

1. Open Word and go to the Review tab.
2. In the Compare group, select Compare, then Compare two versions of a document (legal blackline).
3. Under Original document, choose the earlier version, normally the last version you sent.
4. Under Revised document, choose the version you received.
5. Select More to choose what to compare (for example comments, formatting, and text changes), and under Show changes choose word-level or character-level changes.
6. Select OK. If either file contains tracked changes, Word asks to accept them before comparing; select Yes.

Word shows the result in a new document by default, leaving both source files unchanged. Save it with a name that records both versions, for example "Supply Agreement comparison v3 to v4."

A few practical settings are worth knowing:

• Word level is usually easier to read for negotiation. Character level catches a changed digit or punctuation mark more precisely, which can matter in numbers and defined terms.
• Decide whether formatting changes matter. Including formatting surfaces every font and spacing tweak, which is noise in most rounds but useful in a final execution check.
• Combine is not compare. Word also offers Combine, which merges revisions from several reviewers into one document. That is useful internally, but for checking a counterparty's return you want Compare. Microsoft explains the difference on its compare and merge page.

Dedicated comparison tools and contract platforms do the same job with more automation, especially across many rounds and file types. Our roundup of contract redlining software covers the options. If your team still negotiates by emailing Word files back and forth, our guide to alternatives to emailing Word documents explains where that process breaks down.

How to do this in Bind

In a Bind negotiation you do not have to remember to run a comparison: every round is logged and compared for you. Here is the supply agreement example again.

Step by step, with the names you will see in Bind:

Bind is used by in-house legal teams at companies including Slush, the global startup and tech event organizer, and Atria, listed on Nasdaq Helsinki.

Key takeaways

• A redline proposes; a blackline verifies. The redline is the negotiation document, and the blackline is the comparison that proves what changed.
• Tracked changes show only what was tracked. Edits made with tracking off, accepted before sending, or pasted in wholesale are invisible in a redline.
• Always compare against the last version you sent. That is the only comparison that shows every change since your last position.
• The terms are not standardized. Describe the document you mean rather than relying on "redline" or "blackline" alone.
• Word can do it today. Review, Compare, legal blackline, earlier version as original, later as revised.

For how teams encode their standard positions so every reviewer responds to a redline the same way, see what AI playbooks are in contract management.