Run a simple cash-flow "what if" from your monthly numbers
Give the AI your starting cash, a normal month's money in and out, and one change you're worried about, and it builds a month-by-month table showing when cash would run low, for you to check with your accountant.
- Setup
- 15 min
- Saves
- About 30 min a use (our estimate)
- Level
- Medium
- Last checked
- Works with
- Any AI chat, Spreadsheet
Run once on made-up data on with Claude. One run, not proof.
Version 1 · Draft: not yet approved by the owner · How we testWhat this does
It answers "what happens to my cash if...?" Give the AI your starting cash, a normal month and one change, such as losing a big customer. It builds two month-by-month tables, as normal and what if, and names the first month cash drops below your safety level. You re-check the math and take it to your accountant.
This is not financial advice; check with your accountant. It's a rough planning draft.
Before you start
- Any AI chat, plus a spreadsheet to re-check the math.
- Cash in the bank today, and a normal month's money in and out by type.
- Known one-time bills (insurance renewal, tax payment).
- The safety level you never want cash to drop below.
- Setup: about 15 minutes (our estimate).
- Privacy: round numbers are fine. No account numbers, customer names or staff pay.
Steps
- Write down starting cash and normal monthly money in and out from recent bank statements.
- List the one-time bills coming up and the one change you want to test.
- Paste the prompt into a new AI chat and fill in the blanks.
- Re-add the first two months yourself, or let a spreadsheet add up the table.
- Read the AI's assumptions. Fix any that are wrong and run it again.
- Take the tables to your accountant before a big decision.
The prompt
Help me run a simple cash-flow "what if". Use only the numbers I give you. Don't give investment, loan or tax advice; this is a planning draft for me and my accountant. Don't send anything. Starting cash on [date]: [amount] Normal month, money in: [amount and main sources] Normal month, money out: [list each: rent, payroll, supplies, loan, other] Known one-time items: [month, amount, what] What if: [the change, e.g., "biggest customer, $X a month, leaves starting September"] Months to show: [e.g., July to December] My safety level: [e.g., $5,000] Do this: 1. Make a month-by-month table: money in, money out, net, ending cash. One table for "as normal", one for "what if". 2. Show your math for the first month so I can check it. 3. Name the first month ending cash goes below my safety level, and below zero, if it does. 4. List every assumption you made (for example, costs that might drop with sales). Don't add costs or income I didn't give you. 5. If a number is missing or unclear, write UNCLEAR and ask. Plain words, no jargon.
Before and after: the made-up input, then the real output the AI gave us.
Try it with made-up data
Tidewater Print Shop (made up). Starting cash on 2030-07-01: $18,000. Normal month in: $24,000 (print jobs). Normal month out: rent $3,200, payroll $11,500, supplies $5,400, loan $900, other $2,100. One-time: $2,400 insurance renewal in October. What if: the biggest customer ($6,000 a month) leaves starting September, and a new press lease of $750 a month starts in August. Months: July to December. Safety level: $5,000.
What the AI gave us
Normal month out: $3,200 + $11,500 + $5,400 + $900 + $2,100 = $23,100. July: $24,000 − $23,100 = +$900, so ending cash is $18,000 + $900 = $18,900.
As normal
Month In Out Net End cash Jul 24,000 23,100 +900 18,900 Aug 24,000 23,100 +900 19,800 Sep 24,000 23,100 +900 20,700 Oct 24,000 25,500 −1,500 19,200 Nov 24,000 23,100 +900 20,100 Dec 24,000 23,100 +900 21,000 What if (customer leaves in September, lease from August)
Month In Out Net End cash Jul 24,000 23,100 +900 18,900 Aug 24,000 23,850 +150 19,050 Sep 18,000 23,850 −5,850 13,200 Oct 18,000 26,250 −8,250 4,950 Nov 18,000 23,850 −5,850 −900 Dec 18,000 23,850 −5,850 −6,750 Cash first drops below $5,000 in October ($4,950) and below zero in November (−$900).
Assumptions: Supplies stay at $5,400 even after the customer leaves; if supplies drop with sales, the gap is smaller. Customers pay in the month of the work. No other income or costs. From September, you'd need about $5,850 more a month, in new sales or lower costs, to break even.
Good: the tables matched when we re-added them, and it named the supplies assumption on its own. A person still had to decide how much supplies would really drop, and whether customers pay late (which would push the low point earlier).
Check before you send
- Starting cash and monthly numbers match your bank statements.
- The math adds up when you re-check it in a spreadsheet.
- One-time bills are in the right months.
- Every assumption is true for your business, or you changed it.
- You talked to your accountant before acting on it.
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Don't paste
- Bank or loan account numbers, or logins.
- Customer names attached to what they pay you.
- Individual staff pay or personal finances.
When not to use this
- As a forecast for a loan application. Ask your accountant.
- When income swings a lot. One "normal month" will mislead you; use real monthly numbers.
- For tax planning or deciding whether to borrow. That's your accountant's or adviser's job.
Questions owners ask
What is a cash-flow "what if"?
A table of money in, money out and cash left each month, run as normal and with a change. It shows when cash might get tight.
How far ahead should I look?
Far enough to see trouble coming. Six months is a simple start; your accountant may suggest more.
Sources
Related guides
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