# How to build a 13-week cash flow forecast

List your opening cash, then forecast cash in and cash out for each of the next 13 weeks. Use real due dates for customer receipts and supplier payments. Roll it forward each week and watch the lowest balance.

Free tool: [Cash flow forecast generator](https://www.pulsify.tech/free-tools/cash-flow-forecast-generator/). The generator has a monthly view for 12 months and a weekly view for 13 weeks. Choose Weekly (13 weeks) under Forecast View, set the date week 1 starts and enter your opening cash balance.

## Why it matters

Profit does not pay wages. Cash does. A 13-week forecast shows a cash gap weeks before it arrives, while you can still act.

It works because it uses real dates, not averages. You can see that a BAS payment and a large supplier bill land in the same week.

## The steps

1. **Start with the bank balance.** Use the reconciled balance at the start of week 1.
2. **Forecast receipts.** Use the aged receivables report. Put each invoice in the week you expect payment, based on how that customer actually pays. Add new sales you expect.
3. **Forecast payments to suppliers.** Use the aged payables report and approved bills. Put each in the week of your payment run.
4. **Add wages and super.** Add each pay run. Add the super for it too, which under Payday Super must reach the fund within 7 business days after payday.
5. **Add tax and fixed costs.** Add BAS, PAYG instalments, rent, loan repayments and insurance on their due dates.
6. **Work out net cash and closing balance.** Net cash = receipts - payments. Closing balance = opening + net cash. The closing balance becomes next week's opening.
7. **Set a minimum balance.** Pick the lowest balance you are comfortable with, such as two weeks of wages.
8. **Find the gaps and act.** Chase debts, delay a payment run, ask for terms or arrange finance before the gap week.
9. **Roll it forward each week.** Replace the week just ended with actuals and add a new week 13.

## Worked example

Example Distribution Pty Ltd starts with A$40,000. Here are the first four weeks. The BAS of A$24,090 is due in week 4.

| Week | Opening | Receipts | Payments | Net | Closing |
| --- | --- | --- | --- | --- | --- |
| 1 | A$40,000 | A$22,000 | A$18,500 | A$3,500 | A$43,500 |
| 2 | A$43,500 | A$15,000 | A$21,000 | -A$6,000 | A$37,500 |
| 3 | A$37,500 | A$19,000 | A$26,000 | -A$7,000 | A$30,500 |
| 4 | A$30,500 | A$30,000 | A$52,500 | -A$22,500 | A$8,000 |

Cash falls to A$8,000 in week 4. With a minimum balance of A$15,000 that is a A$7,000 gap. The team has three weeks to collect debts or move a supplier payment.

## Common mistakes

- Forecasting sales instead of cash receipts.
- Using terms instead of real customer behaviour.
- Forgetting tax and super dates.
- Not updating it weekly.

## Common questions

### Why 13 weeks?

It covers a quarter, which lines up with BAS and is short enough to forecast with care.

### Should I include GST?

Yes. Cash moves with GST, so forecast gross amounts and put the BAS payment in as its own line.

### How accurate does it need to be?

Close enough to show gaps. Compare it with actuals each week and learn from the gaps.

## Next step

Use the [Cash flow forecast generator](https://www.pulsify.tech/free-tools/cash-flow-forecast-generator/) first. Then see [Pulsify for finance leaders](https://www.pulsify.tech/solutions/cfo/).

## Sources

- ATO: payment deadlines for Payday Super: https://www.ato.gov.au/businesses-and-organisations/super-for-employers/paying-super-on-payday/payment-deadlines-for-payday-super

Source: https://www.pulsify.tech/how-to/build-a-13-week-cash-flow-forecast/ (last checked 2026-10-21)