Build a 12-week cash flow forecast

Economist · Time: 45 min · Finance

Tools that fit this task

• ChatGPT $20/mo
• Copilot in Excel $20/mo
• Claude $20/mo
• Gemini in Google Sheets $14/mo

Prompt

Role: you are a financial analyst building a cash flow forecast for a small business.
Context: account balance {{amount}} as of {{date}}. Receivables: {{list with client codes, amounts and expected dates}}. Payables: {{list with dates}}. Recurring payments: {{rent, payroll, taxes with dates and amounts}}. Weekly sales plan: {{amounts}}. Assumptions: average payment delay {{days}}, bad debt {{percent}}%.
Task: build a 12-week cash flow forecast in three scenarios: base, optimistic (inflows +15%), stress (inflows minus 15% and payments delayed by another 14 days). Find the first week with a negative balance in each scenario and the three drivers that affect the result most.
Format: three tables week | inflows | outflows | net flow | closing balance. After them, the list of all assumptions you used and five conclusions with specific actions. All amounts in {{currency}}, no rounding to thousands.

Steps

1. Collect the inputs: account balances, receivables with due dates, payables with due dates, recurring payments (rent, payroll, taxes) with dates
2. Write down the assumptions in words: average client payment delay, share of bad debt, the weekly sales plan
3. Give the assistant the inputs and assumptions with a prompt for a weekly forecast skeleton and three scenarios
4. Get a weekly table with inflows, outflows, closing balance and the list of assumptions used
5. Move the skeleton into your own spreadsheet with formulas so the numbers recalculate when assumptions change
6. Ask it to find the week when the balance turns negative in the stress scenario and what drives it most
7. Record the decisions: which payments can be moved, whom to remind about payment, whether a credit line is needed

How to check the result

The forecast recalculates by formula when one assumption changes, the stress scenario shows the specific week of the cash gap, and there is a list of actions with deadlines

Pitfalls

• The model calculates from your assumptions and looks confident: the list of assumptions must be written under the table and checked by you
• Receivables with client names and amounts are a trade secret; they go into a public service with client codes

Data that stays out of public AI tools

• Product cost and margin: a trade secret, into a public service only the table structure
• Budgets and plans before approval: only inside a corporate environment
• Salaries of specific employees in calculations: replace them with averages or codes

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AI tools for economists · Prompt: Build a 12-week cash flow forecast