Compare two versions of a contract with Claude

When the counterparty sends back your contract with edits, Claude can read both versions in full and return a table of every change with an assessment of whom it favors. The job takes about 15 minutes. What Claude adds is judgment about each change; what it lacks is the character-level precision of Word Compare, so the two tools work together.

Where Claude helps and where it slips

Claude reads a large document whole instead of chopping it into pieces, which matters in a contract where clause 14 changes the meaning of clause 3. It answers with references to specific clauses, and it writes precisely, without filler. In a comparison it catches rewritten liability language, a moved termination right or a new condition on payment, and it can tell you which side gains from each edit.

The weak point is small edits. A model skims past "within 5 days" turning into "within 5 business days", and that is often the change the other side cared about most. Run Word's Review, Compare on the same pair and treat its output as the ground truth for numbers and deadlines.

Choosing a plan for legal work

On the free plan you get several dozen messages a day and analysis of uploaded files, enough to compare one pair of versions. Pro costs 20 USD per month, or 17 with annual billing, and adds Projects, so every matter keeps its own versions and instructions. A legal department is better served by Team: 25 USD per seat per month with annual billing, 30 monthly, from five seats, with team data kept out of model training by default. The Max plans at 100 and 200 USD per month only make sense for someone who spends the whole day in Claude.

Prepare the versions

Get both versions as text. Replace party names, amounts and details with placeholders [Party A], [Party B], [amount], and use the same placeholders in both versions, otherwise the model will report the replacement itself as a change. Label them clearly: version 1 is yours, version 2 came from the counterparty.

The prompt

Role: you are a corporate lawyer reviewing a counterparty's edits to a contract. Context: I represent {{our side}}. The contract is a {{contract type}}. Below are version 1 (ours) and version 2 (from the counterparty), with parties and amounts replaced by placeholders. Task: find all changes between the versions, including removed and added clauses and changes in numbers, deadlines and wording. For each change assess whom it favors and what risk it carries for us. Format: a table clause | before | after | favors | risk for us | proposal. As separate lists: removed clauses, new clauses, changes in numbers and deadlines. Leave unchanged clauses out of the table. Version 1: {{version 1}} Version 2: {{version 2}}

State your side in {{our side}}: buyer, supplier, licensee. Without it, the "favors" column is guesswork. {{contract type}} can be as short as "supply agreement" or "lease".

What to do

1. Get both versions as text and replace party names, amounts and details with placeholders [Party A], [Party B], [amount].
2. Run the built-in comparison in Word (Review, Compare) or give both files to an assistant that handles long documents.
3. Ask for a list of all changes by clause with an assessment of whom each change favors.
4. Check every change found against the originals, especially clauses on liability, deadlines, payment and termination.
5. Ask separately for the clauses removed from the new version and the new clauses that did not exist before.
6. Build a table of changes with a decision on each: accept, reject, propose our own wording.

Checking the table

The comparison is finished when every change in the table is found in the original, and a spot check of three clauses the model called unchanged confirms they really match. Pick those three from the clauses that matter most to your side: liability, payment, termination. If one of them differs, rerun the comparison with a narrower request for that section.

Keep the chat lean

Claude's limit is measured by conversation size rather than message count. A long chat with two full contracts spends quota on every question, so open a separate chat for each pair of versions and keep matter materials in a Project. Before the first work document, check Settings, Privacy and make sure training on chats is off.

Contracts and correspondence go in only with parties, amounts and details anonymized. The same applies to your counterparty's comments in the margins if they name people.

If your team drafts in Word all day, see how Claude compares with Copilot in Word. The ready-made template is on the contract comparison prompt page.