How to build a weekly cash forecast with new Claude Opus 5.5

I’m using Opus 5.5 for a week now, and it's a real breakthrough for finance. I’m amazed by its ability to check its work and improve itself like a real CFO analyst.

Every CFO knows this week.

You build the 13-week cash forecast on Monday.

And by Friday a customer has paid late, a vendor has been paid early, and the forecast is already out of date. So you open the spreadsheet and start again.

Why not give this job to Claude Opus 5.5?

I gave it one file with our week 1 cash position, the collections we expect, and the payments already scheduled. It built the 13-week cash flow forecast. Then it tested the forecast, found what was wrong, and fixed it.

But that’s not it.

Plenty of tools can build a forecast. Claude Opus 5.5 checked its own work and improved it, the way a great CFO analyst would.

Anthropic released Opus 5.5 on September 22.

It costs about 40% less to run than Opus 5.

In Anthropic’s test of company earnings reports, where a single made-up figure meant a fail, Opus 5.5 passed 16 of 18 times. Opus 5 and Fable 5.1 didn’t pass once.

When Opus 5.5 and Opus 5 each built the same merger model in Excel and turned it into an executive deck, Opus 5.5’s work was more thorough, took 63 minutes instead of 93, and cost half as much. Opus 5’s version had minor errors.

Today I’ll show you how to use Opus 5.5 as a CFO.

And set it up with a weekly cash forecast (.skill) and one file (.xlsx).

You install the weekly cash forecast (.skill), upload your week 1 cash file, and get a forecast you can update every week and take straight into your board deck.

Let’s dive in.

---

How to build a weekly cash forecast with new Claude Opus 5.5 as a CFO

Download the weekly cash forecast (.skill) below