Copilot's $18 Promo Ends September 30. The Cheaper Path Isn't the Promo

Microsoft's pricing page has a date on it: the promotional $18 per user per month rate for the standalone Copilot Business add-on runs through September 30. After that, the list price is $21, and the monthly-billing version sits at $25.20. Twenty days is exactly the kind of window that makes a small business sign something.

Before you do, look at the path the countdown banner is not showing you.

The three ways to buy the same Copilot

As of this month, a small business on Microsoft 365 has three routes to the same assistant:

1. The with-Copilot bundle plans. Business Standard with Copilot at $23.50 per user per month, Business Premium with Copilot at $32. Against the plain plans, that is an effective increment of roughly $9.50 to $10 per user for Copilot itself. These are permanent SKUs, not promos, and you can assign them per user. We covered the July launch of these plans in Microsoft 365 Copilot pricing 2026.
2. The Business Basic promo bundle. Basic plus Copilot at $21 through December 31, for teams on the cheapest tier.
3. The standalone add-on. Copilot Business at $21 list, $18 on the expiring promo. This is the one with the September 30 clock on it.

Line those up and the deadline loses most of its drama. The add-on's promo price, the one expiring, is still nearly double the bundle route's effective cost. The promo mostly matters for businesses that must stay on their exact current plan and bolt Copilot onto it; for everyone else, the bundle SKUs made the add-on the expensive path back in July.

One more wrinkle from the partner channel: resellers list the same discount running through December 31 rather than September 30. If you buy through a Microsoft partner rather than the storefront, ask before you rush.

The math for a real team

Take a 10-person company on Business Standard at $14. Moving everyone to the with-Copilot plan costs about $95 more per month. The standalone add-on at the expiring promo price costs $180 more per month for the same ten people, and $210 after September 30. Mixed licensing makes the gap smaller in practice, because nobody says every seat needs Copilot: three seats for the people who write proposals, run the books, and answer customers is a $28.50-per-month experiment on the bundle path.

What to do with the deadline

Deadlines are a marketing instrument, and the correct response is a usage question, not a calendar question. If your team has been using Copilot on a trial or a few seats and the drafts are landing, moving to the bundle plans is cheaper than any promo, no date pressure involved. If nobody has touched it, locking in a rate for software your team may not adopt is how AI spend quietly becomes a line item nobody defends; the Software Buying Scorecard exists for exactly this decision, and the AI Spend Auditor for the seats you bought last time under a countdown.

And whichever route you take, the day Copilot lands on every desk is the day your team needs one page of ground rules: what data goes into prompts, which outputs need review before they leave the building. The AI Usage Policy Writer drafts that page in an afternoon.

If you are still deciding whether Copilot is the right assistant at all versus plain ChatGPT, the honest comparison is in ChatGPT vs. Microsoft Copilot for small business; the short version is that the answer depends on how much of your work already lives in Word, Excel, and Outlook, not on which promo expires first.