Copilot shelf

The Real Cost of Copilot

The number your CFO will ask for, and the method that produces it.

One-time. Corrections are re-delivered free.

The free, open-source Copilot prompt library that sits under this work was cited by Jared Spataro (Microsoft, AI at Work) in his 25 February 2026 note. He was citing that free repo when it held 300+ prompts. This is a separate, paid product and he did not review or endorse it.

The situation

A per-seat add-on you can forecast in a spreadsheet. You know that line. You have built chargeback models that survived a CFO.

Copilot Studio broke the pattern. The moment your organisation turns on agents, Microsoft meters Copilot Credits, bills them to an Azure subscription, and settles them against rates you did not choose. The seat invoice lands in one place, the credit consumption in another, the Azure tail in a third, and the data-readiness spend that often dwarfs the licence line shows up nowhere in the plan you approved.

So when finance asks for the real cost of Copilot, you have four bills and no allocation key that ties them together. You can quote the seat price. You cannot defend the total.

What this is

This treats Copilot as what it now is: a consumption product. It shows you how to see the whole cost surface, allocate it across invoices that share nothing, forecast the meter before it runs, and cut it with decisions rather than hope.

What is inside

The four-invoice cost surface, mapped
An allocation key that joins invoices with no shared dimension
A 90-day cost plan
The forecast method for the metered layer

// FROM INSIDE THE PRODUCTChapter 7, Allocation Across Invoices

An Operator Move and a Waste Trap from the allocation chapter

Operator Move. Stand up one billing policy per department, or per major agent owner, rather than one all-users policy. That single design choice is the difference between chargeback and a black box.
Waste Trap. Allocating raw credits as if they measure usage. A zero-rated internal-agent team will look free while an external-agent team looks expensive, even at identical real activity. The fix is to allocate the seat cost that covers the zero-rated work to the team that does the work, and treat the credit line as the metered remainder.

The two are not adjacent. A section called Why raw credits lie sits between them, working through why the seat plane and the metered plane attribute cost to different principals. A third callout type, Meter Check, runs through the book alongside these.

Who it is for

FinOps leads who just inherited an AI line item
IT finance partners who have to defend the total
Anyone who has been asked "so what does Copilot actually cost us"

Who it is not for

Teams who only need the flat seat maths. If nobody has enabled agents, your cost is seats times price and you do not need this yet.

Not sure yet? Start free.

Free sample and credit-estimate worksheet is free and covers the same ground at a smaller scale. If it is useful, this is the full version.

Download Free sample and credit-estimate worksheet

Questions people actually ask

Does this work if we are on E3 rather than E5?

Yes. M365 Copilot is a paid add-on that sits on top of a qualifying M365 licence, so the licence tier underneath changes what data Copilot can reach, not whether this material applies. Where an E5-only control is the cleanest answer to something, the material says so and gives the E3 route as well.

Is this current for the June 2026 GA wave?

Yes. Cowork went generally available worldwide on 16 June 2026 and brought a metered layer billed in Copilot Credits at $0.01 each. Everything here is written against that change rather than around it. When a document is revised, Gumroad re-delivers it to everyone who already bought, free.

What if we have not enabled Cowork yet?

That is the common case and it is fine. The metered layer is additive and off by default until an admin enables it, so your bill today is still flat seats. Reading this before you switch it on is the cheaper order to do it in, because the decisions get harder to reverse once makers start building.

How is this different from The Variable Cost of Copilot?

This one maps the whole cost surface and gets you to a defensible total. The Variable Cost is the deeper companion focused only on the metered layer: the templates, the two calculators, and the chargeback method for the part of the bill that moves. Start here if you need the total, go there if the meter is already running.

Are the prices in it going to be out of date in a month?

The list prices will move, and the method will not. Prices are labelled with their as-of date so you can see what to re-check, which is the point of the label: it tells you what has gone stale without you having to wait for a revision. When one is published, Gumroad re-delivers it free.

Buying this with a company card?

Your receipt email carries a Generate link that opens an invoice generator: add your billing address, put your legal company name and any reference your finance team needs in the Additional notes box, and download the PDF. If you have an EU VAT number, enter it at checkout and no VAT is charged. Here is the approval email, so you do not have to write one.

Approval email

Subject: Approval request: The Real Cost of Copilot ($29, one-time)

Hi [Manager],

I would like to expense a one-time $29 purchase: The Real Cost of Copilot by Kesslernity.

What it is: The number your CFO will ask for, and the method that produces it.

What we get:
- The four-invoice cost surface, mapped
- An allocation key that joins invoices with no shared dimension
- A 90-day cost plan
- The forecast method for the metered layer

Why it is worth it: it is a one-time purchase with no subscription,
and at $29 there is no statement of work, no discovery call and nothing to negotiate.
The author publishes the open-source Copilot prompt library that Microsoft's
CMO for AI at Work cited as "battle-tested in production environments".

A downloadable invoice is available from the purchase receipt for expenses.

[Your name]