A 13-week cash flow forecast estimates the money your business expects to receive and pay over the next three months, one week at a time. It starts with the cash currently available, and it shows the projected closing balance for each week. When updated regularly, this forecast can reveal a potential shortfall while there is still time to respond.
An annual budget may show a profitable quarter, yet leave out the specific week when wages, a supplier payment, and a tax bill all fall due. A weekly forecast brings those critical dates into view. For Australian employers, it should also reflect the move to Payday Super from 1 July 2026.
What Is a 13 Week Cash Flow Forecast?
A 13-week cash flow forecast is a short-term schedule of expected cash receipts and payments. Each week’s closing cash balance becomes the next week’s opening balance. The schedule is usually updated after the week ends: you replace the first week’s estimates with actual transactions, revise the remaining assumptions, and add a new thirteenth week.
The 13-week period is a practical planning horizon rather than an Australian legal requirement. It is close enough for many businesses to accurately estimate payment dates from invoices, payroll, and known commitments, while still looking far enough ahead to see a quarterly tax payment or a delayed customer receipt. Businesses facing rapid changes may also need a daily view of the next few weeks.
A forecast follows cash timing. Revenue belongs in the week a customer is likely to pay, rather than simply the week you issue an invoice. Similarly, expenses belong in the week the money is expected to leave the bank. The Australian Government’s cash flow statement guidance similarly distinguishes between opening cash, incoming cash, outgoing cash, and the closing balance.
Why Forecast Weekly Instead of Monthly?
A monthly forecast can easily hide a cash gap that opens and closes within the same month. Suppose a major client pays on a Friday, but wages and a loan instalment are due on the preceding Tuesday. The month-end position might look sound, even though Tuesday’s obligations still need funding.
Weekly forecasting is especially useful when:
- Customer payments vary: An invoice may be due this week, but the customer’s usual payment pattern points to next week.
- Large costs cluster together: Payroll, supplier deposits, loan repayments, and tax payments can fall close enough to strain the bank balance.
- You are planning an investment: The forecast shows whether a new hire, equipment purchase, or project outlay fits the cash available when the payment is due.
This weekly view perfectly complements a longer-term budget. As business.gov.au explains, a budget sets out the plan, while a forecast uses current information to estimate what is likely to happen next.
What Should You Include in a 13 Week Cash Flow Forecast?
Start with a bank balance you can reconcile. Then group expected movements so the forecast is detailed enough to explain a change, but simple enough to maintain.
| Category | Items to check |
|---|---|
| Opening cash | Cleared balances in accounts available for business payments; identify restricted cash separately. |
| Customer receipts | Outstanding invoices, contract milestones, recurring receipts and expected new sales, dated for likely collection. |
| Operating payments | Supplier invoices, rent, utilities, insurance, subscriptions and other committed costs. |
| People costs | Wages, contractor payments, PAYG withholding and superannuation at the applicable payment times. |
| Tax payments | BAS, GST, PAYG instalments, income tax and other liabilities that fall within the period. |
| Financing and investment | Loan repayments, interest, approved finance receipts, equipment purchases and owner contributions or distributions. |
Account for GST and Unconfirmed Funding
Use one consistent treatment of GST throughout the process. If the receipt and payment rows show amounts including GST, avoid adding the same GST again as a separate expense; instead, forecast the actual net BAS payment or refund at its expected date. The government’s cash flow guidance also recommends making it clear whether estimates include or exclude GST.
Do not treat an undrawn credit facility, proposed loan, or unsigned contract as cash already available. Show any realistic funding option separately, along with its assumptions and approval status.
Account for Payday Super in 2026 and Beyond
Since 1 July 2026, Australian employers have had to calculate and pay the super guarantee with each payday. The general rule is that contributions must reach the employees’ super funds within seven business days of payday, subject to some exceptions. The cash forecast should show exactly when the business expects the money to leave its account, while payroll processes must also allow enough time for the funds to arrive by the applicable deadline. Always check the ATO’s Payday Super guidance for the specific rules that apply to your business.
A template still showing only quarterly super payments can therefore overstate the cash available between pay runs. Because of this, historical payment patterns need adjusting before they are used to forecast the next 13 weeks.
How Do You Build a 13 Week Cash Flow Forecast?
The first version does not need to be elaborate. However, it does need dependable inputs and an owner who will consistently update it.
- Set the opening balance: Reconcile your bank accounts and identify any amounts that cannot be used for ordinary payments.
- Place known receipts in the correct weeks: Use invoice due dates as a starting point, then adjust for actual customer payment patterns and any disputed amounts.
- Enter committed payments: Use payroll schedules, supplier terms, loan agreements, lease dates, and confirmed tax obligations. Check the due dates on the business’s ATO activity statements rather than applying a generic BAS date.
- Estimate less certain movements: Base expected new sales and variable spending on current orders, recent trading, and seasonality. Be sure to label all assumptions clearly.
- Calculate the closing balance for every week: Add expected receipts to the opening cash, and subtract expected payments. Carry the result forward, then review the lowest point of the period, not just the final balance at week 13.
- Refresh it after each week: Replace estimates with actual receipts and payments, investigate any material differences, and extend the forecast by one week.
For Australian businesses, the ATO’s BAS due-date guidance states that the applicable lodgment and payment date is shown directly on the activity statement. This date may depend on the specific reporting cycle and individual circumstances. Ultimately, a forecast should reflect the business’s own unique obligations.
What Does a Weekly Forecast Look Like?
The figures below are purely illustrative. They show why the lowest balance matters more than the total receipts across the period.
| Week 1 | Week 2 | Week 3 | |
|---|---|---|---|
| Opening cash | $40,000 | $30,000 | $10,000 |
| Expected receipts | $20,000 | $15,000 | $20,000 |
| Expected payments | $30,000 | $35,000 | $32,000 |
| Projected closing cash | $30,000 | $10,000 | -$2,000 |
Week 3 exposes a $2,000 funding gap under these assumptions. This does not mean the bank balance can automatically go below zero; rather, it means the business needs to confirm the timing of receipts, review payments, or arrange an appropriate funding solution before that week arrives. If several large transactions fall on different days of the same week, you should check the daily position as well.
What Should You Do When the Forecast Shows a Shortfall?
Start by finding out whether the gap is likely to occur and how much time the business has to respond:
- Check the assumptions: Confirm customer collection dates and payments that cannot move. Run a second scenario if an overdue invoice may arrive later than expected.
- Review what you can change: Follow up on debts, discuss agreed supplier terms, defer discretionary spending, or revisit the timing of a purchase. Discuss an existing finance facility if appropriate.
- Address tax payments directly: Keep tax liabilities in the forecast. If the business cannot pay an ATO amount when it is due, review the ATO’s support and payment options.
A forecast is a planning tool, not proof that a company is solvent. If a company may be unable to pay its debts when they fall due, directors need prompt, qualified advice. ASIC’s information for directors explains the duty to prevent insolvent trading and identifies poor cash flow, overdue taxes and superannuation, and a lack of forecasts among the possible warning signs.
How Often Should You Update the Forecast?
Update a rolling forecast at least weekly. Each review should cover three main things:
- Actual results: Replace the completed week’s estimates with the actual receipts and payments that occurred, and investigate any material differences.
- Changed assumptions: Revisit expected customer payments, signed work, fixed costs, and approved funding. Move amounts to new weeks when the timing changes.
- A new final week: Add week 13 so the forecast always looks ahead across the same consistent period.
If the business has little cash headroom, volatile collections, or a near-term payment risk, review the immediate days more often. A forecast loses its value quickly when the underlying assumptions are left untouched.
Plan the Next 13 Weeks With Mizael Partners
A useful forecast does more than just produce a closing balance. It gives your business a clear view of which payments are coming, which receipts remain uncertain, and when a decision is needed.
Mizael Partners’ CFO advisory services include cash flow forecasting and financial oversight. If your business needs a dependable weekly view of its cash position, contact Mizael Partners to discuss its forecasts and reporting.
This article provides general information as at 28 September 2026. Cash flow forecasts depend on their assumptions and do not replace advice about a business’s tax, financing, or solvency position.