Audit a financial model’s formulas before you rely on it

---
name: spreadsheet-formula-audit
description: "Use when the user shares a financial model or spreadsheet and wants its formulas checked for hardcoded numbers, broken ranges, inconsistent formulas and circular logic before it is relied on. Triggers: audit my model, check formulas, inherited spreadsheet, model review before a lender or board."
---

# Audit a financial model’s formulas before you rely on it

Have an assistant look for hardcoded numbers, broken ranges, inconsistent formulas and circular logic in a model you inherited or built in a hurry.

## When to use it

Before a model goes to a lender, a board or a buyer, and whenever you inherit one. The errors that matter in a model are rarely exotic: a number typed over a formula, a SUM that stops one row short, a growth rate that's different in one column.

This works best with an assistant that can read the workbook itself, like Claude for Excel or Copilot in Excel, because it can see every formula. In a plain chat, upload the file if your assistant accepts spreadsheets, or paste the formulas as text.

**Where it works.** Works in Claude, ChatGPT, Copilot or any AI assistant. No setup.

## Ask the user for

- The workbook, or the formulas from the sheets that matter.
- Which cells are meant to be inputs, if the model doesn’t mark them.
- What the model is for, so the review weighs the right outputs.

Ask for anything missing before you start. Never invent a figure to fill a gap.

## Do this

Carry out the request below. Fill each [bracketed] item from what the user gave you.

Audit this financial model. It's used for [purpose: a lender's covenant forecast, a board budget, a valuation]. The outputs that matter most are [cells or lines].

Check for:
1. Hardcoded numbers inside formulas, or typed over a row that's otherwise formulas.
2. Ranges that stop short of or run past the data (a SUM that misses the last row).
3. Formulas that change partway across a row where the pattern should be consistent.
4. Circular references, and whether they look deliberate.
5. Inputs that aren't marked as inputs, and outputs that depend on them.
6. Totals that don't tie between sheets.

For each finding give the sheet and cell, what's there, why it's a problem, and the fix. Rank them by how much they could move the outputs that matter. Don't change anything in the workbook; just report.

## Before you hand it over

Tell the user which of these checks they still need to make:

- Go to each cell named and look for yourself before you change anything.
- Decide whether “inconsistent” formulas are errors or deliberate. The assistant can’t know intent.
- After fixing, re-tie the outputs that matter to their prior values and explain every change.

The assistant drafts. The person whose name is on the work approves it.

## What a good answer looks like

**1. Forecast!N14 (high impact).** Revenue for December is typed as 184,000. Every other month in row 14 is `=M14*(1+$C$4)`. At the model's growth rate December would be 191,256, so annual revenue is understated by 7,256.

**2. Summary!D22 (high impact).** `=SUM(D8:D20)` skips row 21 (Other income, 3,400 a month).

**3. Forecast!H30:N30 (medium).** Payroll uses a 3% raise from July on; months before it use 0%. That could be deliberate. Confirm it matches the plan.

**4. Inputs (low).** The DSO assumption in Assumptions!C9 isn't shaded as an input, and three sheets depend on it.

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From the Harbinger FinLab skill library: https://harbinger.finance/skills/spreadsheet-formula-audit