More businesses fail from cash flow problems than from lack of profitability. A business can be generating genuine accounting profit — recording revenue, showing a margin — and still run out of money if the timing of cash inflows and outflows is not actively managed. Cash flow forecasting is the tool that prevents this from happening.
This guide is written for founders and business owners who want a practical, usable approach — not a theoretical one.
Why Cash Flow Forecasting Matters
Profit and cash are not the same thing. Profit is an accounting concept that records revenue when it is earned and costs when they are incurred, regardless of when money actually changes hands. Cash is what sits in your bank account.
The gap between profit and cash is created by:
- Accounts receivable timing — you have invoiced the customer but not yet been paid
- Accounts payable timing — you have received goods or services but not yet paid for them
- Inventory — cash tied up in stock that has not yet been sold
- Loan repayments — principal repayments are a cash outflow but not a P&L expense
- Capital expenditure — buying equipment or fit-out consumes cash before it appears as depreciation expense
- Tax timing — BAS, PAYG, and income tax payments create lumpy, periodic cash outflows
A cash flow forecast makes all of these visible, in advance, so you can plan around them.
The 13-Week Rolling Cash Flow Forecast
The most practical format for SME cash flow forecasting is the 13-week rolling forecast. This gives you a three-month forward view — long enough to identify upcoming pressure points, short enough to be reasonably accurate.
The forecast is rebuilt or updated weekly, so it always looks 13 weeks ahead. As each week passes, a new week is added at the far end.
What to Include
Cash inflows:
- Expected receipts from existing debtors (based on invoice dates and payment terms)
- Expected new sales receipts (based on revenue forecasts and expected payment timing)
- Any other expected cash inflows (asset sales, loan drawdowns, grant receipts)
Cash outflows:
- Payroll (including super, which is due quarterly but should be accrued weekly)
- Rent and occupancy costs
- Supplier payments (based on invoice dates and payment terms)
- BAS and tax obligations
- Loan repayments
- Capital expenditure planned
- Any other known outflows
Net cash movement:
- Weekly opening balance + inflows - outflows = closing balance
- Closing balance becomes next week's opening balance
The Key is Specificity
A useful cash flow forecast is specific, not vague. Rather than estimating "sales receipts" as a round number, work from your actual debtor ledger: who owes you money, how much, and when are they likely to pay? Rather than estimating "supplier payments," look at your actual creditor ledger and payment terms.
The more you work from real data — actual invoices, actual payment terms, actual payroll dates — the more accurate and useful the forecast becomes.
Building Your First Forecast
If you have never built a cash flow forecast before, here is a practical starting point:
Step 1: Establish Your Opening Position
Start with your actual bank balance today, plus any funds in offset accounts or short-term deposits that you can access quickly. This is your opening cash position.
Step 2: Map Your Debtor Book
Pull your aged receivables report. For each invoice or debtor balance, estimate when you expect to receive payment based on payment terms and the debtor's actual behaviour (some customers habitually pay late — use reality, not invoice terms).
Step 3: Map Your Known Outflows
Go through your forward commitments: payroll dates, rent due dates, supplier payment terms, known BAS or PAYG obligations, and any loan repayments. Put these in the weeks they will actually leave your bank account.
Step 4: Estimate Future Revenue Receipts
Based on your sales pipeline or revenue forecast, estimate what new cash will come in over the next 13 weeks and in which weeks it is likely to land (accounting for payment terms).
Step 5: Calculate the Running Balance
Build a simple spreadsheet with weeks as columns and inflows/outflows as rows. Calculate the running balance week by week. Any week where the balance goes negative — or dangerously close to zero — is a problem you need to plan around now, not scramble to address when it arrives.
Common Warning Signs in a Cash Flow Forecast
Once you have a forecast in place, here are the red flags to watch for:
- Consecutive weeks of negative cash movement — your cash is being systematically drained
- A cliff in a specific week — a large payment (BAS, tax, rent review) that will significantly deplete your balance
- Debtors who consistently pay much later than terms — these are distorting your cash inflow timing
- Rising gap between profit and cash — may indicate inventory build-up or accounts receivable blowout
Connecting the Forecast to Action
A cash flow forecast is only useful if it changes behaviour. When you can see a cash crunch approaching in week seven, you have time to:
- Accelerate receivables collection — chase debtors, offer early payment discounts, tighten payment terms for new clients
- Defer discretionary spending — push back non-essential purchases or capital expenditure
- Arrange facility headroom — speak to your bank about a line of credit or overdraft facility before you need it (not in a crisis)
- Negotiate with suppliers — request extended payment terms from key suppliers
The most expensive time to arrange finance is in a crisis. The most effective time is when you can see the problem three months away.
Software Options for Australian SMEs
Most accounting software platforms — Xero, MYOB, QuickBooks — have some cash flow forecasting functionality built in, though it is often limited. More sophisticated tools include Float, Fathom, and Futrli, which connect to your accounting software and provide more granular forecasting.
That said, for many SMEs, a well-structured Excel or Google Sheets model, updated weekly, is sufficient to get the job done. The discipline of updating it matters more than the sophistication of the tool.
Cash flow forecasting is not complex. But it does require consistency, honesty about timing, and the discipline to keep it current. For businesses that build this habit, the payoff is enormous: you move from reactive to proactive, from surprised to prepared. That shift alone is worth the effort.
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