Building Financial Models Faster with AI

AI won't build your financial model for you — but it can dramatically speed up the structural work, formula writing, error checking, and documentation. This lesson covers practical AI applications across the financial modelling workflow.

Where AI Fits in the Modelling Process

Financial modelling has several stages, each with different AI applications:

Stage	AI can help with
Planning the structure	Layout design, tab structure, input/output architecture
Formula writing	Complex formulas, dynamic calculations, array functions
Assumptions documentation	Writing clear assumption descriptions
Sense-checking	Logic review, common error checking
Scenario analysis	Structuring scenario tables, describing outputs
Model commentary	Explaining outputs in plain English

Designing Model Structure

Before building, use AI to think through architecture:

"I need to build a 3-year financial model for a [type of business]. Key inputs: [list]. Key outputs: [list]. Suggest the tab structure, the logic flow between tabs, and any commonly missed line items for this type of model. Flag any structural pitfalls I should avoid."

This is especially valuable when you're building models for unfamiliar business types.

Formula Writing

This is the highest-value immediate application. Describe what you need in plain English:

"Write an Excel formula that:

• Looks up a customer name from column A in a table on the 'Rates' sheet
• Returns the corresponding rate from column C of that table
• If the customer isn't found, return the default rate from cell B2 on the 'Rates' sheet
• Use IFERROR to handle errors cleanly"

"Write an Excel SUMIFS formula that sums values in column D where:

• Column A matches a date range (from B1 to B2)
• Column B equals 'Actual' (not 'Budget')
• Column C is not empty"

"Write a dynamic array formula that returns a unique list of all division names from column B, sorted alphabetically."

Always test the formula in your actual spreadsheet — AI can get the syntax right but may not know your exact column structure.

Checking Your Model Logic

"Here is the logic for my revenue model:

[describe your model structure or paste a simplified version]

Review this for:

1. Logic errors or circular reasoning
2. Commonly missed items in this type of model
3. Any assumptions that seem aggressive or likely to be challenged
4. Presentation issues that would confuse a reviewer"

Writing Assumption Documentation

"I have the following assumptions in my financial model:

• Revenue growth: 8% year 1, 12% year 2, 10% year 3
• Gross margin: 42% improving to 45% by year 3
• Overhead costs: Fixed at £800k, growing 3% pa thereafter

Write clear, professional documentation for each assumption that explains: what it is, the rationale for the level, and key sensitivities. This is for a document accompanying the model to be reviewed by the CFO and potentially lenders."

Scenario Analysis Design

"I'm building a scenario analysis for a 3-year business plan. The business is [describe]. Key uncertainties are revenue growth and gross margin.

Design a scenario analysis with:

• A base case, upside, and downside
• Suggested assumptions for each
• The 3 most important output metrics to track across scenarios
• A brief description I can include in the model notes for each scenario"

Explaining Model Outputs

"My financial model shows the following 3-year projection:

[paste key outputs — revenue, EBITDA, cash flow, etc.]

Write a 200-word explanation of these projections for a bank lender considering a loan. Highlight the key assumptions, the peak debt requirement, and the repayment capacity."

Your Turn

Pick a formula you find yourself writing repeatedly. Describe it to ChatGPT or Claude in plain English and ask it to write it for you. Then ask it to add error handling. This single habit will save you real time every week.