What it means
The word model sounds grander than the reality. At its heart a cash flow model is a grid with time across the top, categories of receipts and payments down the side, and a running balance at the bottom that carries forward from one period to the next.
It matters because profit and cash are different things, and only cash pays the wages. A business can report a strong month while its bank balance falls, because customers pay on 60-day terms and suppliers expect payment in 30, and a cash model is what makes that gap visible in advance.
The most common formats are a 13-week rolling model for short-term control and a monthly model covering twelve to thirty-six months for planning and lender reporting. The 13-week version is deliberately detailed on receipts and payables, while the longer version is driven by revenue assumptions and cost budgets.
Building one starts with the opening bank balance, then layers in customer receipts based on sales and payment terms, followed by payments grouped into payroll, suppliers, tax, interest and capital spending. Each period's closing balance becomes the next period's opening balance, which is what turns a list of numbers into a forecast of when cash runs short.
The most valuable output is often not the central case but the low point: the worst closing balance across the horizon, and the date it occurs. Boards use that figure to size an overdraft, time a funding round or decide whether a capital purchase can wait a quarter.
In practice
Real-world examples
Example 1
A restaurant group builds a weekly cash model before opening a second site and sees the balance dipping to $18,000 in week nine, before the new kitchen reaches steady trading. The owners negotiate a deferred rent-free period to cover the dip.
Example 2
A manufacturer preparing for a bank refinancing produces a 24-month monthly model showing the loan repayment schedule against projected receipts. The bank uses the low point in the model to set the covenant on minimum cash balances.
Example 3
A recruitment agency uses a rolling 13-week model updated every Monday, because it pays contractors weekly but invoices clients monthly. The model tells the director exactly how many new contractor placements the cash position can support.
Think of it
A cash flow model is your forecasting tool for predicting future cash ins and outs.
Formula
Calculation
Closing Cash = Opening Cash + Total Receipts - Total Payments, with each period's closing balance carried forward as the next period's opening balance.
A design agency starts the quarter with $250,000 in the bank.
Month 1: Opening $250,000, receipts $480,000, payments $525,000. Closing = $250,000 + $480,000 - $525,000 = $205,000.
Month 2: Opening $205,000, receipts $510,000, payments $495,000. Closing = $205,000 + $510,000 - $495,000 = $220,000.
Month 3: Opening $220,000, receipts $540,000, payments $610,000, including an annual insurance premium and a corporation tax instalment. Closing = $220,000 + $540,000 - $610,000 = $150,000.
The model shows the agency ending the quarter with $150,000, having fallen $100,000 over three months despite two of them being cash-positive on receipts alone.Case study
Seen in the real world
This fictional illustration follows Copperfield Joinery, an invented bespoke furniture maker with a strong order book and a persistent overdraft. The owner could not understand why a profitable business kept running out of money.
An advisor built a simple monthly cash flow model covering the next twelve months. It showed that deposits were collected at order, but the timber and hardware for a commission were paid for in the following month while the final 60% of the customer invoice arrived three to four months later. Every new order therefore consumed cash before it produced any.
Once the pattern was visible, the fix was straightforward. The owner moved to a 40% deposit and a 30% payment at the start of assembly, and the model showed the low point rising from a $62,000 overdraft to a positive $15,000. The business grew its order book the following year without increasing its facility.
Watch out
Common mistakes
- Building the model from the profit and loss account and calling it a cash forecast, which ignores payment terms, tax timing and capital spending entirely.
- Forgetting irregular but certain payments such as annual insurance, tax instalments and bonus payments, which are usually the cause of an unexpected shortfall.
- Never comparing the model against what actually happened, so the same optimistic collection assumptions get repeated every month.
Questions
People also ask
How far ahead should a cash flow model run?
A 13-week rolling model suits day-to-day control, while twelve to twenty-four months is the usual horizon for planning and lender reporting.
Should VAT and sales taxes appear in a cash flow model?
Yes, they are real cash movements with their own payment dates, and leaving them out is a frequent cause of forecast error.
Does a small business really need one?
Yes, and arguably more than a large one, because a small business has less headroom to absorb a timing gap it did not see coming.
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