Building Your First Copilot Skill in Excel for a Repeatable Month End Close

Every close I have ever run has the same problem hiding inside it: the process lives in someone's head. The order in which you refresh the trial balance, book accretion, amortise prepaids, layer in the tax provision, then reconcile before anyone touches a support file — that sequence is real, it matters, and until now it was almost impossible to hand to a machine without writing brittle macros. That changed in June, when Microsoft [introduced Skills to Copilot in Excel](https://www.microsoft.com/en-us/microsoft-365/blog/2026/06/25/copilot-in-excel-built-for-the-era-of-frontier-finance/), letting teams package a repeatable workflow as reusable instructions the model follows every time.

A Skill is not code. It is an open-standard markdown file that describes, in plain language, how you want a task done. Think of it as the close checklist you already keep, rewritten so Copilot can execute against it instead of a junior analyst rediscovering it each month. Microsoft's own finance organisation runs these across FP&A, accounting, tax and treasury before the features ever reach the public, and [CFO Dive reported](https://www.cfodive.com/news/microsoft-boosts-copilot-excel-based-finance-workflows/823933/) the first library covers exactly the work that eats our week: building a DCF, closing the books, refreshing a monthly model, running variance analysis.

Here is how I would build the first one. Start with a close you have already done well and treat it as the golden reference. Open a new markdown file and write the steps as instructions, not descriptions: name the source tab, state that accretion is booked before the tax provision, specify that every journal carries a reference and a one-line rationale, and tell Copilot to stop and flag anything it cannot tie out rather than guessing. Be explicit about format, because a Skill that produces a clean, review-ready output is worth ten that produce something you have to unpick.

The payoff is consistency you can actually trust. When the same instructions drive the same steps in the same order, the output stops drifting between preparers, and your reviewer spends time on judgement instead of hunting for what moved. Partner-built Skills are arriving in Q3, but the ones worth owning are the proprietary ones that encode how your entities close.

At Cell Fusion Solutions Inc we build these close Skills for finance teams and stress-test them against a real prior period before they touch a live book. If your month end still lives in one person's memory, that is the thing to productise first.