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Copilot · 16 September 2026 · 8 min read
The frontier models write better. Copilot knows your company. For an organisation whose data lives in Microsoft 365 the decision is about where the data goes and who governs it — and the pattern that works is not either-or.
Most companies on Microsoft 365 already have people using ChatGPT or Claude at work, usually on a personal account, usually by pasting. The question the IT lead gets asked is whether to buy one of those properly, buy Microsoft 365 Copilot, or both. This is an honest answer from a company that sells Copilot and uses all three, and it is not “Copilot is the best model” — it is often not. It is that for a company whose data lives in Microsoft 365, the decision is mostly about where the data goes, not about which model writes the better paragraph.
The model. ChatGPT and Claude are the frontier: on writing, reasoning and code, both are at least as capable as what Copilot uses, and on any given week one of them is ahead. Copilot runs on OpenAI models with Microsoft’s orchestration; the model inside it is not the reason to buy it.
Where it can look. This is the difference that matters. Copilot reads your Exchange, SharePoint, OneDrive and Teams through Microsoft Graph, with the user’s own permissions: “summarise everything the client sent since March” works because it can see the mailbox. ChatGPT and Claude see what is pasted or uploaded, or, with their enterprise connectors, a subset of the same sources through a separate integration you configure and secure. Out of the box, Copilot knows your company; the others know what you tell them.
Where the data goes. With Copilot, prompts, files and answers stay inside the Microsoft 365 service boundary, under the same terms as your email: no training on your data, EU Data Boundary for European tenants, sensitivity labels and Purview data-loss prevention applied to what it produces, every interaction in the audit log, Conditional Access deciding who can use it from where. With ChatGPT Enterprise or Claude for Enterprise the vendors make comparable no-training and encryption commitments and can pass the same security review — but it is a second vendor, a second identity, a second data-processing agreement, and the connectors into Microsoft 365 are yours to configure and govern. With a personal ChatGPT or Claude account, which is what most companies actually have today, the data leaves under consumer terms, and that is the situation to end first, whichever product replaces it.
Where it appears. Copilot is a button in Word, Excel, Outlook, Teams and PowerPoint, in the file the person already has open. The others are a browser tab or a desktop app; the work is copy in, copy out. For a finance analyst in Excel or a lawyer in a Word precedent, that is the whole difference in adoption.
Governance. Copilot is administered where the rest of the tenant is: licences per user in the admin centre, Purview policies, Entra ID, audit. It is one line on the invoice from the partner you already have. The others are a separate contract, SSO integration to set up, and a separate audit trail to collect.
For any organisation whose files and mail are in Microsoft 365 and whose work happens in Office, Teams and Outlook: the value is in the grounding, not in the model. A summary of a 200-message thread, a draft from the firm’s own precedents, a variance explained in the actual spreadsheet — these need access to the data, and Copilot has it by default, with the permissions the company already maintains. Add that it inherits the security posture instead of needing a new one, and for the finance and legal teams that will veto anything else, that settles it.
Three cases, and they are real. Software development: the frontier models in a coding tool — Claude in an IDE, GitHub Copilot, which is a different product with a confusing name — are ahead of Microsoft 365 Copilot, which is not built for code. Long-form writing and analysis that starts from a blank page rather than from company documents: a marketing team drafting a campaign, an analyst working through a 300-page report they uploaded; the frontier models are simply better writers and readers of long documents. Anything outside Microsoft 365: if the data is in Google Workspace, Salesforce or a data warehouse, Copilot cannot see it without agents and connectors, and a tool with the right connector may be the shorter route.
The pattern that works is not either-or: Microsoft 365 Copilot for the organisation, on the plan it already has, and a handful of enterprise seats of a frontier model for the developers and the writers who need one — on enterprise terms, with SSO, and with the personal accounts switched off.
Whatever you buy, the first action is the same: find out who is pasting company data into personal AI accounts, and give them a sanctioned tool before you block anything. Microsoft 365 Copilot Chat — the free tier included with Business and Enterprise plans, grounded on the web and, with a Copilot licence, on your data — is the sanctioned alternative that costs nothing; Purview can then flag uploads to consumer AI sites. Blocking without an alternative moves the pasting to a phone.
Microsoft 365 Copilot: €26 per user per month annual, or €18.20 on a Business plan — for 100 people on Business Premium, €21,840 a year on top of the plan. ChatGPT Enterprise and Claude for Enterprise are quoted by the vendors, typically in the same range per seat with minimum seat counts. Twenty developer or writer seats on one of them plus Copilot for everyone is a common and defensible shape; buying a frontier model for everyone and no Copilot means buying the model without the data, which is the expensive way to get less.
Related: Which Copilot? The six compared · Copilot at work: five companies, five departments · Copilot Studio: agents inside your tenant · Price Copilot with your plan.
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