How to Use Claude for FP&A: The Petra Skill Guide

Financial planning and analysis is the quiet engine room of a company: budgets, rolling forecasts, the monthly variance report that explains why the plan and reality disagree. Reach for Claude for FP&A with a one-line prompt and you get numbers with no narrative — figures that do not explain themselves to the people who have to act on them. A real AI FP&A analyst is judged on the story it tells about the numbers, not just the numbers.

Petra is built for that. She is an FP&A persona you load once into Claude, ChatGPT, or any AI chat, and she treats every figure as something that has to be explained, not just produced. Below is what actually changes when she runs the cycle with you.

The monthly close, without the dread

The variance report is where most FP&A time disappears: pulling actuals against budget, then writing the commentary that says why. Petra structures the variance analysis and drafts the commentary in plain business language — not “unfavourable variance of 12%” but what drove it and whether it is a timing blip or a real problem. You review and sharpen rather than start from a blank page.

Forecasts you can actually defend

She builds rolling forecasts and budgets with the assumptions stated openly, so when someone asks “why this number?” the answer is in the model, not in your memory. She runs the scenarios — base, upside, downside — and shows which drivers move the outcome, so the conversation is about the few inputs that matter rather than every cell.

The board pack, translated

Finance lives in detail; leadership needs the headline. Petra turns a dense model into a board-ready summary — the three things that changed, what they mean, and what to watch — pitched for people who do not live in spreadsheets. The same analysis, told twice, for two audiences.

Getting the most out of it

Give her your real actuals and budget and your own assumptions rather than asking her to guess them. Ask for the commentary alongside the numbers, since the explanation is the point. And ask her to flag every figure she has estimated, so you know exactly what to verify before it reaches anyone senior.

Who it is for

FP&A analysts who want their evenings back, finance leads in small companies wearing the whole function, and founders who need a budget and forecast they can stand behind. It works with Claude, ChatGPT, or any AI chat that accepts a system prompt. For the surrounding work, the legal & finance skills collection covers modelling, reporting, and analysis — each a focused assistant rather than a general chatbot. Its outputs explain and structure the numbers; they are not financial advice, and figures should be verified before any decision.