How to model financial scenarios and sensitivities with AI

Finance & FP&A3 AI tools7 steps6 friction points

Financial scenario modeling is the practice of building multiple versions of your future — a base case, an upside, a downside — and stress-testing your assumptions before a decision locks you in. For most operators, it shows up before a hiring push, a pricing change, a fundraise, or a vendor contract. The question is always some version of: what does our cash position look like in 12 months if X happens instead of Y?

AI feels like a natural fit here because the core mechanics are logical, not creative. You're essentially asking: given these inputs, what do the outputs look like under different assumptions? Large language models are decent at arithmetic, can hold multiple scenarios in context at once, and can explain the logic behind a number in plain English — which is often what you need to communicate findings to a board or co-founder, not just produce a spreadsheet.

ChatGPT, Claude, and Gemini can all contribute meaningfully to this workflow. They can build scenario tables from numbers you paste in, apply sensitivity rules, flag which assumptions move the needle most, and format results in a way that's readable to non-finance stakeholders. The ceiling is that they work on data you bring to them, not data they can pull themselves — and they don't remember anything from the last time you ran the exercise.

Finance & FP&A3 AI tools7 steps6 friction points
AI walkthrough

How to do it with AI today

A practical walkthrough using ChatGPT, Claude, and other off-the-shelf LLMs — what they're good at, what you'll have to do by hand.

Tools that work for this
ChatGPTClaudeGemini
Step-by-step
1 Export your current financials: pull a P&L from QuickBooks or NetSuite, grab your bank balance from Plaid or your bank portal, and export your revenue data from Stripe. You need actual numbers — the AI can't fetch them.
2 Paste your monthly actuals into Claude or ChatGPT with a brief description of your business model: current MRR, monthly burn, headcount, and any major upcoming expenses. Keep it under 2,000 words to stay well inside context limits.
3 Ask the model to establish a base case: current trajectory extended 18-24 months, with burn and revenue growth held constant at your trailing 3-month average. Verify the arithmetic before moving forward.
4 Define the variables you want to stress-test — hire two engineers next month, raise prices 15%, delay the fundraise 6 months, lose your top customer. Prompt the model to build a separate scenario for each, showing runway, end-of-period cash, and break-even month.
5 Ask for a sensitivity table: which single assumption, if it moves 10% in the wrong direction, has the biggest impact on runway? This forces the model to rank your risks, not just enumerate them.
6 Request a plain-English summary of each scenario's implications — one paragraph per scenario — suitable for a board update or investor memo. Claude tends to produce cleaner prose here than ChatGPT for financial narrative.
7 Copy the outputs into a spreadsheet or Notion doc manually. There's no automatic handoff — you'll paste the table, check formulas, and format it yourself before sharing.
Prompts you can copy
Here are my actuals for the last 6 months [paste data]. Build a base case 18-month projection assuming 8% MRR growth and flat headcount. Show monthly cash balance and runway.
Now build three scenarios: (1) I hire 3 people in month 2, (2) I raise prices 20% but churn increases by 15%, (3) my largest customer churns in month 3. Show runway and end-of-period cash for each.
Create a sensitivity table showing how runway changes if monthly burn increases by 10%, 20%, or 30%, and if MRR growth is 5%, 8%, or 12%. Use my base case as the starting point.
Which assumption in my model moves the break-even date the most if it's wrong by 20%? Rank the top 4 by impact and explain why each one matters.
Write a 3-paragraph board update summarizing these three scenarios in plain English. Assume the reader understands startup finance but hasn't seen our model before.
Reality check

Where this gets hard

The walkthrough above works — until your numbers change, the LLM hallucinates, or you have to re-paste everything next month.

No live data connection — every session starts with you exporting CSVs or copying numbers manually. If your books changed yesterday, your model is already stale.
Nothing persists between sessions. The scenario structure you built last month exists only in your chat history. Next quarter you rebuild it from scratch.
Large datasets hit context limits. If your transaction history runs long or you're modeling at line-item granularity, the model truncates or loses earlier assumptions mid-response.
Outputs drift in structure between runs. The table format you got from ChatGPT on Tuesday looks different from what Claude returns on Thursday, requiring manual reformatting each time.
No version control on assumptions. If you change a growth rate mid-session, there's no clean record of what changed, when, or why — which makes auditability difficult when a stakeholder asks how you got a number.
Sharing requires manual export. The scenario output lives in a chat window. Getting it into a format you can share, update, or return to means copying, pasting, and reformatting by hand every time.

Tired of the friction?

Starch runs the whole workflow on live data — no copy-paste, no hallucinated numbers, no re-prompting next month.

See the Starch version →
Starch alternative

The same workflow on Starch

Starch is an agentic operating system — it builds and runs persistent software on your live business data. For financial scenario modeling, that means an agent builds a live app connected to your actual Stripe revenue and Plaid bank data, not a prompt you re-run against last month's export.

Start with the Scenario Analysis app from Starch's App Store — it connects Stripe and Plaid on a scheduled sync so your baseline always reflects real revenue and real burn, not numbers you pasted in this morning.
Adjust assumptions in plain English and see the impact immediately. Tell Starch 'show me what happens to runway if I hire two engineers in Q3 and revenue growth drops to 6%' — the model updates without rebuilding anything.
The Runway Analysis app runs alongside Scenario Analysis, giving you a live burn rate and 24-month projection that refreshes daily from your connected accounts — so your base case is never manually maintained.
Add the Budgeting app to compare planned spend against actuals from Plaid as the quarter progresses. When a scenario assumption drifts from reality, you see it in the budget variance, not at the end of the quarter. (Currently in beta — request access.)
Describe any custom scenario structure in plain English and Starch builds it as a persistent app. 'Build me a side-by-side view comparing three fundraise-timing scenarios with runway, net burn, and break-even month for each' — the agent builds that dashboard and keeps it live against your connected data.
Share a live link to the scenario dashboard with co-founders or investors instead of exporting a static table. The data updates automatically; you're not re-running prompts before every board meeting.
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Toolkit

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