Copilot vs ChatGPT for a Microsoft 365 company
Checked · Re-check by
Use included Copilot Chat first; pay for Microsoft 365 Copilot's work search or ChatGPT Business across tools.
| What matters | Copilot | ChatGPT |
|---|---|---|
| Seat price / terms | Chat: included. Paid: £13.80/mo annual promo + VAT + base. | Business Standard: US$20/mo annual; US$25/mo monthly + tax. |
| Company information | Chat: supplied files / app context. Paid: work search. | Business: uploads / approved sources, within permissions. |
| Where it works | Chat: apps by label. Paid: full Microsoft 365 apps. | Business: ChatGPT / supported apps. Test the handoff. |
| Data controls | Chat / paid: no foundation training. | Business: no training by default. |
Included Copilot Chat is not the paid add-on
Use a work account with a qualifying Microsoft 365 business or enterprise subscription. Included Copilot Chat can use web information and files you supply. App context is different from searching across company information: Outlook can use work context without the add-on. Microsoft now shows Copilot Chat (Basic), M365 Copilot (Basic) and M365 Copilot (Premium) labels. Basic app access varies by label and tenant; it isn't safe to say all included users lack Word or Excel help. The paid Microsoft 365 Copilot add-on gives the full app experience with priority access and broader work search when work-data grounding is on. It still respects the user's permissions. Check the label under your name before buying something you already have. Microsoft is also shortening some product names to Microsoft Copilot during a transition. This comparison keeps the licensing distinction explicit.
What the seat prices actually buy
Checked 9 November 2026: Microsoft's UK Business add-on lists £16.10 per user/month paid yearly, discounted to £13.80 for the first year, excluding VAT. The offer runs 1 July to 31 December 2026, needs an existing eligible Microsoft 365 Business plan and an annual commitment, excludes trials and other offers, and can change. It auto-renews; the base subscription costs extra. Monthly billing lists £19.32 excluding VAT. Some advanced features add usage charges. ChatGPT Business Standard lists US$20 per user/month billed annually or US$25 monthly; Premium lists US$100 per user/month billed annually or US$125 per user/month billed monthly. The advertised starting minimum is two paid seats; billing documentation notes eligible single-seat exceptions, so check signup. These are USD reference prices, not a confirmed GBP quote or a currency conversion. VAT depends on checkout and Tax ID status; confirm the final local invoice. No OpenAI promotion is assumed in these prices.
Microsoft 365 job or cross-tool job?
Start with included Copilot Chat for a supplied-document summary or draft. Test paid Microsoft 365 Copilot when finding information across Microsoft files, messages and meetings, then finishing inside its apps, is the missing step. Test ChatGPT Business when the job spans supported services as well as uploaded files. Its Company Knowledge plugin needs an installed, allowed plugin and authorized sources; buying a seat doesn't connect your company. SharePoint can search supported work OneDrive content too, within existing access. ChatGPT workspace approval and Microsoft Entra consent are separate, and your administrator may need to grant the latter. Supported actions vary by app and settings, so finding a file doesn't prove the tool can edit or deliver it. These are recommendations from documented access boundaries, not a benchmark or a claim that Matt uses either paid option for Microsoft 365 work.
Data controls still need a human decision
Microsoft says business Copilot Chat and paid Copilot prompts and responses aren't used to train foundation models. They are logged, and available controls depend on your underlying subscription. Generated Bing web searches have separate handling from Microsoft 365 prompts and responses. OpenAI says ChatGPT Business inputs and outputs aren't used for training by default. That doesn't grant access to a file: app permissions, account authorization and workspace controls still apply. Review any third-party app's terms before connecting it. For this week's test, allow only the sources and read actions the job needs, then check the output against the originals. A data-protection promise isn't proof a total is right or permission to send a document.
What would change this recommendation
Change the choice if your same-input test shows a paid option saves enough correction and handoff time to cover the full bill. Recheck when Microsoft changes included app access, work-search licensing or this promotion, or OpenAI changes Business seat terms, supported sources or action permissions. If your admin can't approve the required connection, that option doesn't finish your job today. Matt's dated personal sprint setup below is separate from this buying recommendation; it isn't evidence that either vendor won this test.
What I'd use in a sprint
Opus 5.5 on xhigh to plan, Sonnet 5.5 on medium or high to build, Opus 5.5 on medium or GPT-6.1 on high for harder tasks.
Matt's own setup, 1 November 2026. His choice, not a ranking of which models are best.
How to test it this week
- Day 1: pick one weekly job, such as a project update. Make a fictional brief, email thread and spreadsheet with known totals and two deliberate contradictions. Use identical sanitized copies and the same prompt in each option you can access.
- Day 2: test included Copilot Chat with the files supplied explicitly. Record which facts it can cite, which contradictions it notices and how many edits a person needs to make. Don't count a plausible answer without a source as correct.
- Day 3: if you already have an approved paid Microsoft 365 Copilot seat, repeat with the same files in a test SharePoint site and the same user's permissions. Test finding the files without uploading them. Record the exact license label and any disabled settings. Don't buy seats just to complete this test.
- Day 4: repeat in ChatGPT Business with the same uploads, then with an approved read-only SharePoint connection if available. Check admin consent first. With a second test account that lacks access to one fictional file, confirm neither connected tool retrieves it. Never weaken permissions to make a test pass.
- Day 5: compare source accuracy, totals, where the final file lands and human correction time. Check every proposed edit before saving or sending. Keep the included option unless a paid option finishes the job with fewer corrections and enough time saved to justify its full cost. A tie proves no reason to switch.
Sources
- https://www.microsoft.com/en-gb/copilot/pricing/business · Checked
- https://support.microsoft.com/en-gb/microsoft-365-copilot/how-copilot-chat-works-with-and-without-a-microsoft-365-copilot-license · Checked
- https://learn.microsoft.com/en-us/copilot/plan/copilot-overview · Checked
- https://learn.microsoft.com/en-us/copilot/plan/privacy-and-protections · Checked
- https://learn.chatgpt.com/docs/pricing · Checked
- https://help.openai.com/en/articles/8542115-chatgpt-business-general-faq · Checked
- https://help.openai.com/en/articles/8792536-managing-billing-and-seats-in-chatgpt-business · Checked
- https://help.openai.com/en/articles/11487775-connected-apps-in-chatgpt · Checked
- https://help.openai.com/en/articles/12143177-sharepoint-app-and-setup-in-chatgpt · Checked
- https://help.openai.com/en/articles/12628342/ · Checked
- https://openai.com/business-data/ · Checked
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