Last week I was still bouncing a client memo between the browser and Word. Clean a paragraph, paste it back, watch the numbering fall apart. Around September 19 that loop got shorter: OpenAI shipped ChatGPT as a Word add-in, and Free plans can install it.
The same contract or weekly update can now sit next to three assistants: Microsoft Copilot, OpenAI’s ChatGPT, and Anthropic’s Claude. The buttons look alike. They do not see the same things.
Free to open, not free of limits
OpenAI’s help center is plain about it: ChatGPT for Word is on every ChatGPT plan, including Free. There is no separate install fee. Open the ChatGPT listing on Microsoft Marketplace, choose Get it now, then open ChatGPT from the Word ribbon and sign in. If you use an organization workspace, pick that workspace. Word, Excel, and PowerPoint share one add-in.
“Free plans included” is not “unlimited.” Usage is token-based and depends on the model, document size, and the job you ask for, counting input, cached input, and output. Word draws from the shared allowance used by Codex and other premium features on plans that include them. Heavy editing in Word leaves less of that allowance for everything else. A two-page memo on Free is usually fine. Rewriting a full contract over and over is how you hit the cap.
There is also a short promo. IT Home reported on September 19 that Business and Enterprise customers can try GPT-5.6 Sol in Word from September 17 through September 30, and that preview usage does not count against normal limits. If you are reading this on September 28, two days are left.
What the sidebar can actually touch
The help center lists concrete jobs: turn notes into a memo, proposal, or report; summarize or write an executive summary; revise a section for another audience; reorganize content and adjust headings, numbering, and formatting; flag unclear language and inconsistent terms.
Select the text first, then say what should change and what must stay. For a bigger rewrite, ask for an outline or a description of the edits before anything lands in the file. I learned that after it expanded a client’s defined acronym and broke the rest of the draft.
The limits matter more than the feature list.
Complex formatting, tables, and charts often need a manual pass. ChatGPT for Word can work with the open document. It cannot see other files on your computer unless you paste the relevant text. Connectors such as Outlook, SharePoint, Google Workspace, and Dropbox depend on your plan, workspace settings, and permissions. Plugins are not supported.
Two easy misses: conversations in the add-in are separate from your ChatGPT history, and memory and skills do not carry over. It can also change lines you meant to keep. Save a copy before a large edit, and check figures, citations, and conclusions before you send the file.
Data handling follows your plan. In Business, Enterprise, and Edu workspaces, inputs and outputs are not used to train OpenAI models by default. Personal plans follow the data controls on that account. Landing in Word does not put the file inside your company’s vault.
Three AIs, three doors
| Copilot | ChatGPT for Word | Claude for Word | |
|---|---|---|---|
| How it gets in | Microsoft’s own assistant in Word | Marketplace add-in, ChatGPT login | Anthropic add-in, Claude login |
| Who can use it | Depends on a Copilot seat | Every ChatGPT plan, including Free | Every paid Claude plan |
| What it sees by default | Mail, SharePoint, and collaboration data when the org allows it | The open document; anything else needs a connector or a paste | The open document; Anthropic says context can move across open Office files |
| How it edits | Writes into Word | Sidebar draft, rewrite, proofread, format | Tracked changes, comment replies, company styles |
Copilot is the one to ask whether this weekly update matches last week’s email and the budget file in SharePoint. ChatGPT is the one to use when you already have an account and do not want a Microsoft seat just to rewrite a section. Anthropic’s page describes Claude for Word as tracked changes, comment replies, and edits that follow company styles. Excel, PowerPoint, and Word are generally available on all paid Claude plans. Outlook is still in beta.
My split is blunt. Use Copilot when the answer depends on company files. Use ChatGPT to draft, change tone, or cut a section for an executive. Use Claude when the other side needs to see exactly which sentence changed. If you are not on a paid Claude plan, leave it off today’s shortlist.
You can install all three. That does not mean all three should rewrite the same paragraph. I keep the version that changes the least and leaves the facts alone.
Copilot and ChatGPT will both show up in the ribbon. Ignore the icons. Ask whether this sentence needs other company files. If yes, open Copilot. If you are only rewriting what is on the page, open ChatGPT. If the other side must see the edits, open Claude.
On a company PC, it turns on by default October 1
A personal copy of Word is a straight install. A company tenant is not.
Admins on both sides can block it. A ChatGPT workspace admin can turn the Word entry off in the admin console. A Microsoft 365 admin also has to allow the add-in before it shows up in the ribbon. The help center says ChatGPT for Word will be enabled by default starting October 1, 2026. If you want it off, or only on for some people, do that before staff are already signed in.
The wrong workspace looks like a missing install. The account has to match, and so does the workspace.
FAQ
Do I need a Copilot license?
No. This rides on the ChatGPT account, not a Copilot seat.
Is Free unlimited?
No. It uses your plan’s allowance. Longer documents and repeated rewrites burn it faster.
Separate add-ins for Word, Excel, and PowerPoint?
No. One ChatGPT Microsoft add-in covers all three.
Will my document train the model?
It follows your plan and data controls. Business, Enterprise, and Edu are excluded from training by default. Personal accounts follow that account’s settings.
Run three prompts on a real file before you decide: “Write an executive summary of this document. Include the recommendation and the main risks.” “Shorten this section for an executive audience. Keep the facts and defined terms.” “Turn these notes into a client memo with clear headings.”
Which one is open in your Word right now?