The workbook · START HERE plus six tabs
Inside the CFO Brain 13-Week Cash Workbook
The CFO Brain 13-Week Cash Workbook is a plain .xlsx file with a START HERE guide and six working tabs. You type your cash today and the cash you expect in and out each week for 13 weeks. It shows your weeks of cash, your cash floor, your lowest week, and what a hire does to both. You update it in 15 minutes every Friday. It needs no account and no bank login.
US$149 one time. Any VAT or sales tax is added at checkout. A standard .xlsx file, checked in Apple Numbers. Not yet checked in Excel or Google Sheets.
- 33.3 weeks of cash, read from the 13-week forecast.
- Cash floor 50,000: two months of fixed costs.
- Low point 36,550 in week 13: what the OK hides.
Look inside
What is on each tab
The pictures use the example business: made-up numbers that ship inside the workbook. Use the arrow keys to move between tabs.
Your first 15 minutes
Explains the six tabs, the five-step Friday routine, the one rule (set your cash floor before you build the forecast) and the colour code: yellow cells are yours, grey and green calculate.
- Yellow cells are yours.
- Set your floor first.
Your weeks of cash
Type four things: cash in the bank today, money customers owe you, money you owe, monthly fixed costs. It shows weeks of cash from your 13-week forecast, how long you would last if sales stopped tomorrow, your minimum cash floor, and your lowest point with the week it falls in.
- 33.3 weeks of cash, read from the 13-week forecast.
- Cash floor 50,000: two months of fixed costs.
- Low point 36,550 in week 13: what the OK hides.
Thirteen weeks of cash in and out
Cash in and out by category: collections, payroll, suppliers, rent, software, taxes, debt. The direct method lists real cash in the week it moves, not accounting adjustments, so you can see which week gets tight. Ending cash rolls forward and the week cash first hits zero is shown.
- Week 3 collects 3,000, not 7,000.
- Week 6: tax 8,500, ending cash 40,600.
- Ending cash 36,550 in week 13, 13,450 under the floor.
What you planned vs what happened
Each Friday, log what actually came in and went out. When a line misses in the same direction three weeks running, it says so, for example "Collections short 3 weeks running."
- Flag: collections short 3 weeks running.
- Forecast 7,000; actual 6,400, 6,600, 6,700.
How many days your cash is tied up
Days to get paid, days stock sits and days you take to pay, set against typical ranges, plus your cash conversion cycle. In the example, collecting 10 days faster releases about 10,100.
- 35.6 days to get paid.
- Cash conversion cycle 9.6 days.
- Collecting 10 days faster releases about 10,100.
Test a decision before you make it
Base, bear and bull cases built from your own forecast. Type a new monthly cost. In the example, a 5,000 a month hire takes 33.3 weeks to 20.3, and to 10.9 in a bad quarter.
Shown with 5,000 typed into the new monthly commitment cells. The file ships with zero there.
- Base case 20.3 weeks with a 5,000 a month hire.
- Bear case 10.9 weeks: TIGHT.
- Type one number: the new monthly commitment.
Three prompts with your numbers in them
One for before money moves, one stress test, one variance review. The formulas do the arithmetic; an assistant you choose can explain the result. Copy a prompt into ChatGPT, Claude or Gemini. Nothing is sent unless you paste it yourself.
- Three prompts, already filled with the example numbers.
- Nothing is sent unless you paste it yourself.
Day one
Your first 15 minutes
DASHBOARD: four numbers
Type cash in the bank today, money customers owe you, money you owe, and your monthly fixed costs. Set the currency cell.
DASHBOARD: set your cash floor
Set "Months of fixed costs to hold" before you forecast. Two is a common start.
13-WEEK DIRECT: your first weeks
Set the date your own week 1 ends, then replace weeks 1 to 4 with your own cash in and out. Rough numbers are fine for now.
Back to DASHBOARD: read it
Read your weeks of cash, your "if sales stopped tomorrow" number and your low point. Fill weeks 5 to 13 in a second sitting.
Every week
Every Friday, 15 minutes
Anchor to your actual bank balance
Type it into the dashboard. Never carry last week's projection forward.
Log last week
Type last week's actual receipts and payments into the variance log.
Read the flags
A line that misses in the same direction three weeks running is an assumption to fix, not bad luck.
Roll the 13 weeks forward
Copy, don't cut. Paste one column to the left and type your new week 13.
Copy the new week-1 forecast
Into the next empty row of the log, ready for next Friday.
Get the free Friday kit: a calendar reminder with these steps.
A 27-second tour
Six stills, a caption on each tab. You press Play; nothing moves by itself. The example business, made-up numbers.
DASHBOARD: Weeks of cash, from the 13-week forecast. The floor and the low point: 36,550 in week 13. 
13-WEEK DIRECT: Week 3 collects 3,000 instead of 7,000. Week 6 pays 8,500 in tax, under the floor from then on. 
VARIANCE LOG: Forecast against actual, week by week. Flag: collections short 3 weeks running. 
WORKING CAPITAL: Days that cash is tied up: a 9.6 day cycle. Collecting 10 days faster releases about 10,100. 
SCENARIO TEST: Add a hire: a new monthly commitment of 5,000. Base case 20.3 weeks. Bear case 10.9 weeks, TIGHT. 
AI PROMPTS: Prompts that fill in your own numbers. Before you commit, stress test, variance review.
Transcript: the captions, in order
- DASHBOARD: Weeks of cash, from the 13-week forecast. The floor and the low point: 36,550 in week 13.
- 13-WEEK DIRECT: Week 3 collects 3,000 instead of 7,000. Week 6 pays 8,500 in tax, under the floor from then on.
- VARIANCE LOG: Forecast against actual, week by week. Flag: collections short 3 weeks running.
- WORKING CAPITAL: Days that cash is tied up: a 9.6 day cycle. Collecting 10 days faster releases about 10,100.
- SCENARIO TEST: Add a hire: a new monthly commitment of 5,000. Base case 20.3 weeks. Bear case 10.9 weeks, TIGHT.
- AI PROMPTS: Prompts that fill in your own numbers. Before you commit, stress test, variance review.
324
formulas you can read
In a plain .xlsx file. Tabs are protected without a password: unprotect one to read any formula.
See the tabs.xlsx
plain file, no macros
No code runs in the file. It is a plain spreadsheet that opens in the app you already use.
How it is checked0
accounts, no bank login
You type your numbers into a file on your computer. This site loads its fonts, pictures and scripts from itself and sets no cookies.
What stays with you
Fit
Who it is for, and who it is not
It is for
- Businesses that invoice and wait to be paid, or pay for stock before it sells.
- The owner decides hires, stock orders and spending.
- Roughly 1 to 30 people. The numbers are inputs, so size does not matter much.
- You will give it 15 minutes on a Friday.
It is not for
- Businesses paid at the till (cafés, salons, most retail).
- Pre-revenue startups living on investor money: that is a different runway question.
- Anyone who wants a bank feed or a tool that updates itself.
- Tax advice or bookkeeping. This is planning.
- A business already in acute insolvency trouble: talk to a lawyer or an insolvency adviser first.
A workbook, not an AI agent. The formulas do the arithmetic; an assistant you choose can explain the result.
What CFO Brain is notIt is not accounting, bookkeeping or tax advice. It does not connect to your bank or your accounting software, so it only knows what you type. It is not a forecast you can hand to a lender as audited. If you are in serious financial difficulty, talk to a lawyer or an insolvency adviser first.
Questions about the workbook
What exactly do I get?
A plain .xlsx file with a START HERE guide and six working tabs: DASHBOARD, 13-WEEK DIRECT, VARIANCE LOG, WORKING CAPITAL, SCENARIO TEST and AI PROMPTS. 324 formulas.
How long does it take each week?
About 15 minutes, every Friday: type in your actual bank balance, log last week's real cash in and out, read the flags, and roll the forecast forward one week. Your first weeks-of-cash number takes about 15 minutes. Filling all 13 weeks properly takes longer the first time, so do it in two sittings.
Does it work in my currency?
Yes. The workbook has no currency symbol, so it works in dollars, euros, pounds or shekels. You set your currency once on the dashboard and the AI prompts use it. The simulator has a currency selector; it changes the symbol only and does not convert.
Excel, Google Sheets or Numbers?
A standard .xlsx file, checked in Apple Numbers. Not yet checked in Excel or Google Sheets. There are no macros.
Is this financial, tax or legal advice?
No. CFO Brain is a planning tool. Tax amounts and dates come from you or your accountant; the workbook only shows when the money leaves. Check important decisions with your accountant or tax adviser.
Who is it for, and who is it not for?
For businesses that invoice and wait to be paid, or pay for stock before it sells, where the owner decides hires and spending. Not for businesses paid at the till, pre-revenue startups living on investor money, anyone who wants a bank feed, or anyone who needs tax advice or bookkeeping.
Is this an AI CFO?
No. CFO Brain is a spreadsheet workbook, not an AI agent. The formulas do the arithmetic. The AI PROMPTS tab holds three prompts with your numbers already filled in; you can copy one into an assistant you choose and ask it to explain the result. Nothing is sent anywhere unless you paste it.
Get the free 13-week starter
One 13-week tab. A standard .xlsx file, checked in Apple Numbers. Not yet checked in Excel or Google Sheets. It opens with an example business already filled in, so you can see the week its cash drops under the floor before you type a number. It shows your runway in weeks and the week your cash is lowest.
Download the starter (no email)- A 13-week cash line with the week your cash is lowest
- Your runway in weeks
- No account, no bank login
Want the full system instead? See what is inside.
Get the starter and the Friday routine by email
Plan your cash 13 weeks ahead.
Know your number. Watch it move. Decide with the weeks in front of you.