Microsoft Copilot for a 15-person office: $21 a seat, an annual commitment, and the math on 4 seats vs 15

The short version

• Copilot Business is Microsoft's add-on for companies with up to 300 users. It lists at $21 per user per month, and every seat is a 12-month commitment.
• It works inside Outlook, Word, Excel, PowerPoint and Teams, using your own mail and files. The free Copilot Chat does not.
• Buy 3 to 5 seats for heavy writers first. Licensing all 15 on day one is the most common way to waste $2,000.

1. What it is

Microsoft sells three different things called Copilot. Owners mix them up, and the bill depends on which one you mean.

• Copilot Chat. A chat assistant that Microsoft makes available to Microsoft 365 business users at no extra cost. It answers from the web and from files you give it.
• Copilot Business. The paid add-on for small and mid-sized companies, launched in December 2025. It puts Copilot into Outlook, Word, Excel, PowerPoint and Teams and grounds it in your company's mail, calendar, files and chats.
• Microsoft 365 Copilot (enterprise). The same capabilities for companies over 300 users.

Microsoft's FAQ says Copilot Business "delivers the same capabilities" as the enterprise offering. The difference is price and the 300-seat cap.

2. Who can buy it

You need Microsoft 365 Business Basic, Business Standard or Business Premium. Copilot Business is an add-on to one of those, and you can add it to plans without Teams. The cap is 300 seats per tenant.

The commitment is the part to read twice. Microsoft's FAQ says Copilot Business is "available as an annual commitment with either monthly or annual billing; there's no month-to-month purchasing agreement." You can add seats at any time. You cannot drop them until the term ends.

3. What it costs

As of October 2026:

• List price: $21 per user per month, paid yearly. Microsoft kept this price unchanged when it raised several Microsoft 365 prices on July 1, 2026.
• Promotion: Microsoft's pricing page showed a promotional $18 per user per month for the first year on annual billing, running through December 31, 2026. Check the page on the day you buy.
• Monthly billing: $25.20 per user per month.
• Bundles from July 1, 2026: Microsoft's own table lists Business Basic plus Copilot Business at $28, Business Standard plus Copilot Business at $35, and Business Premium plus Copilot Business at $43, per user per month paid yearly.

4. A worked example: a 15-person accounting office

A 15-person accounting and payroll office in Ogden runs Microsoft 365 Business Standard. Four partners and managers write most of the client email and review most of the documents. Six staff accountants work mostly in tax and payroll software. Five admin staff handle scheduling, billing and the front desk.

Option A: license everyone. 15 × $21 × 12 = $3,780 a year, all committed. If billed monthly at $25.20, it is $4,536 a year.

Option B: license the heavy users. 4 × $21 × 12 = $1,008 a year. These four draft long client emails, summarise Teams meetings and pull numbers into Word. If each saves 2 hours a month at a $35 hourly cost, that is $280 a month against $84 in seats.

The break-even. At $35 an hour, a $21 seat pays for itself at about 36 minutes saved a month. Most people who write daily clear that. Most who do not, do not open it.

Microsoft's admin center shows Copilot usage per user. Check it at 60 days. Add seats for the people who are asking for it, not by headcount.

5. What to fix before you turn it on

Copilot can only see what each user can already see. That is the safety model and the risk. If your SharePoint has a folder of payroll files shared with "Everyone," Copilot will happily summarise it for the front desk.

Before rollout, spend 4 to 8 hours on three checks:

1. Find files and folders shared with the whole company or with anyone who has the link.
2. Lock down HR, payroll and partner folders.
3. Remove ex-employees and stale guest accounts.

This is worth doing even if you never buy Copilot.

6. What it does well, and what it does not

Good at: drafting replies in Outlook from the thread, summarising a Teams meeting into action items, turning notes into a client letter in Word, building a first-draft deck.

Middling at: Excel analysis. It helps with formulas and summaries. Check every number it gives you.

Not for: anything in software outside Microsoft 365 unless you connect it. It does not know what is in your practice management or field-service system by default.

7. Copilot or ChatGPT or Claude?

If your office lives in Outlook and Teams, Copilot's advantage is that it is already there and already sees your mail. ChatGPT Business and Claude Team cost about the same per seat and can connect to Microsoft 365, but they sit outside it. If half the office would rather use ChatGPT, do not buy both for everyone.

8. What to do

1. Run the sharing clean-up first.
2. Buy 3 to 5 seats for the heaviest Outlook and Word users. Take the promotion if it is still live.
3. Write down hours saved per person at 30 and 60 days.
4. Add seats before renewal only for people with real usage.

Sources and method

• Microsoft Learn, Copilot Business FAQ (eligibility, 300-seat cap, annual commitment), updated August 25, 2026: https://learn.microsoft.com/en-us/microsoft-365/copilot/copilot-business-faq
• Microsoft Tech Community, "Act Now: Lock in Current Pricing on Microsoft 365 Copilot Business Bundles," March 17, 2026 (July 1, 2026 bundle prices, $21 list): https://techcommunity.microsoft.com/blog/microsoft-copilot-blog/act-now-lock-in-current-pricing-on-microsoft-365-copilot-business-bundles/4502628
• Microsoft Copilot plans and pricing page, checked October 5, 2026 (promotional $18 through December 31, 2026; $25.20 monthly billing): https://www.microsoft.com/en-us/microsoft-365-copilot/pricing
• The Ogden office is a composite worked example. Hours saved and the $35 hourly cost are assumptions for illustration.