Microsoft Copilot plans, the two caps, and open source without seats

The rule that sorts the plan list

Microsoft's plan list looks longer than it is. Every paid edition attaches to a base plan a company already owns, and that base plan, not the feature table, decides which edition a tenant can buy.

The Business pricing page states the condition in its footnote: the add-on "is available only to existing Microsoft 365 customers with an eligible Business plan", sold on an annual commitment (Business plans, read 21 October 2026). The enterprise page prices its seat the same way and expects a qualifying Microsoft 365 plan underneath. No tier sells a company edition on its own.

Eligible bases for the smaller tier are Microsoft 365 Business Basic, Business Standard, Business Premium, Microsoft 365 Apps for Business and Microsoft Teams Essentials, as Microsoft's plan options list them. Read that list first. A tenant on Business Basic and a tenant on Apps for Business pay the same add-on price and sit on different apps.

Microsoft 365 E7 closes the loop from the other side. The E3, E5 and E7 comparison marks Copilot as included in E7 and as an add-on in E3 and E5. A tenant that already runs E7 buys no Copilot seat at all.

Two caps, and the price on each side

The first cap counts heads. Microsoft's plan options state that Copilot Business "supports up to 300 seats per tenant" and send larger organisations to the enterprise options. At seat 301 the same assistant moves to another line of the price list, and the base plan under it moves too.

Prices read on 21 October 2026 from the Business pricing page. The seat is $21.00 per person a month on an annual commitment, or $25.20 month to month. A first-year offer takes it to $18.00 until 31 December 2026. Budget the $21.00. The $18.00 is a discount on year one, not the rate the second invoice carries.

Two bundles sit on the same page, and both replace the base plan and the add-on with a single line. Business Standard with Copilot is $23.50 per person a month, $28.20 on monthly billing. Business Premium with Copilot is $32.00, or $38.40 monthly. For a team already set on Standard, the bundle is the cheaper way to buy the pair.

The second cap is the ceiling of the Business family, and the enterprise page prices the step over it at $30.00 per person a month, paid yearly, on a qualifying enterprise plan. Schools and government tenants get their own eligible lists, published beside the commercial one.

The label under a name settles it in a minute

Once a tenant owns something, the question narrows to what a person already holds. Microsoft's Copilot overview defines three in-product labels, and they read the same in Word, Excel, PowerPoint, OneNote and the Copilot app.

Copilot Chat (Basic) is the baseline that ships with an eligible Microsoft 365 plan. It has web-grounded chat and no Copilot inside the four apps. Microsoft 365 Copilot (Basic) adds standard access to Copilot inside Word, Excel, PowerPoint and OneNote without the paid add-on. Microsoft 365 Copilot (Premium) means the add-on is assigned, with priority access to the full experience in those apps and work-data grounding through Microsoft Graph and Work IQ.

A person can read the label at the bottom of the Microsoft 365 home page after signing in with the work account. For a whole tenant, the assigned plans in the admin centre answer the same question in bulk, and Microsoft's service plan diagnostic tool tests one account against the prerequisites.

Buying nothing is a real answer

Copilot Chat is included at no additional cost with eligible Microsoft 365 plans, and the Business page's own answer says so: web-grounded chat, plus Copilot in Outlook and in the Copilot app. A team that wants a meeting recap, a summary of a long thread or a first draft of a reply can stop there and buy no seat at all.

The label Copilot Chat (Basic) is what those people hold, and it is also the limit. Chat has no Copilot inside Word, Excel, PowerPoint or OneNote, cannot ground an answer in the tenant's mail and files unless the content is handed to it, and leaves out the pre-built Researcher, Analyst and Facilitator agents.

So the test is where the work starts. If people paste a document into a chat window, no plan beats the one included. If the work begins inside a document and needs that file's context, the add-on is what buys it, and the arithmetic above decides which add-on.

What the same decision looks like with no base plan

Kortix takes the prerequisite out of the question. There is no base plan to qualify for and no 300-seat line to cross, because nothing is sold per person. Open source. Read it, fork it, audit it. Run it on Kortix Cloud, in your VPC, or on your own on-prem network. Self-host is free.

What a plan normally rations, a repository records instead. Per-resource permissions for people and agents. Roles, groups, and an audit trail. An agent's block names the connectors, skills and secrets it may reach, an omitted grant resolves to none, and the whole list is reviewed like code because it is code.

The entry price is a credit balance, not a seat count. Free is $0 with 500 credits per month, every feature and 1 project, on the user's own provider keys or ChatGPT subscription.