Forecasting & FP&A

Set up a 13-week cash flow forecast

Build a week-by-week cash forecast from your AR and AP agings, payroll calendar and fixed payments, with clear assumptions and a minimum-cash alert.

Time
About 1-2 hours to set up
Level
Intermediate
Works with
Claude, ChatGPT, Microsoft Copilot, Gemini

What you need

  • Opening cash balance
  • AR aging and AP aging (replace customer and vendor names with codes)
  • Payroll calendar and amounts
  • Debt service, rent, taxes and other recurring payments
  • Known one-time receipts and payments

Steps

  1. Collect the inputs and replace names with codes like "Customer A".
  2. Paste the prompt. Answer the AI's clarifying questions before it builds.
  3. Build the model in Excel from the structure it gives you, keeping assumptions in separate cells.
  4. Each week, roll the forecast forward and compare actual cash to the forecast.

The prompt

Fill in the highlighted brackets
Help me build a 13-week cash flow forecast for a [industry] company.

Opening cash as of [date]: $[amount]
Minimum cash we want to keep: $[amount]
Line of credit: $[limit] with $[drawn] drawn

Data:
[paste AR aging by bucket, AP aging by due date, payroll calendar, recurring payments, one-time items]

Before building, ask me up to five clarifying questions about anything missing or unclear.

Then lay out a week-by-week model with:
- Receipts: collections from each AR aging bucket using explicit collection-rate assumptions, plus other receipts
- Disbursements: payroll, AP by due week, rent, debt service, taxes, other
- Net cash flow, beginning and ending cash, and line of credit availability
- A flag in any week where ending cash falls below the minimum

List every assumption separately so I can change it, and give the Excel formulas for the structure.

Review before you use it

  • Week 1 opening cash ties to the bank balance.
  • Collection rates are based on your actual collection history, not optimism.
  • Payroll and tax dates match the real calendar, including bonus or quarterly payments.
  • A weekly forecast-versus-actual comparison is in place.

Never paste into an AI tool

  • Customer and vendor names (use codes)
  • Bank account numbers
  • Use a business or enterprise AI plan that does not train on your data, and follow your company's AI policy.

Educational content, not professional advice. AI output can be wrong; review it before relying on it. Disclaimer