How to prepare a 13-week cash flow forecast
A 13-week cash flow forecast is useful because the week you run short of cash matters more than the quarter you finish in surplus.
For Australian business owners, the task is to estimate when money will actually arrive and leave, calculate the cash available each week and investigate any shortfall before payments fall due. The forecast is a planning tool—not a guarantee of receipts, a substitute for accounts or a reason to borrow a particular amount.
What does a 13-week cash flow forecast show?
A weekly forecast follows cash over 13 consecutive weeks, roughly one quarter. Each column covers a defined seven-day period. It begins with usable opening cash, adds receipts, subtracts payments and carries the closing balance into the next week.
The 13-week horizon is a practical format, not a universal legal rule or lender requirement. It can reveal an approaching payroll, supplier or tax payment that a quarterly total conceals. A longer forecast may still be needed for seasonality, expansion or annual commitments.
Step 1: Define the scope and reconcile opening cash
Choose the business entity, bank accounts and first week covered. Reconcile bank balances to the relevant start date. Identify restricted funds separately; do not assume every dollar appearing in a bank account is available for operations.
Where several accounts are included, transfers between them are not new receipts or expenses for the combined forecast. Keep business and personal transactions identifiable. For a group, ask your accountant whether each entity also needs its own forecast: a consolidated surplus does not prove cash can legally or practically move to the entity with the payment due.
Show available finance separately from cash. An unused limit, an application in progress or a hoped-for owner contribution should not become a balancing figure that makes the forecast appear healthy.
Step 2: Gather records before estimating
Recent bank statements and bank reconciliations.
Aged receivables, outstanding invoices and customer payment history.
Aged payables, supplier invoices and purchase orders.
Payroll schedules, rent, utilities and recurring direct debits.
Tax and superannuation obligations confirmed with the appropriate adviser.
Existing loan schedules, equipment commitments and planned owner withdrawals.
Sales orders, settlement schedules and known seasonal changes.
Use these records to explain the forecast rather than simply dividing last quarter’s receipts and expenses by 13. A regular weekly average can obscure a large bill paid once a month or a customer who settles invoices in batches.
Step 3: Forecast receipts on collection dates
List existing customer invoices by the week they are realistically expected to be collected. Consider the invoice due date, customer history, any dispute and direct confirmation where appropriate. An overdue invoice is not automatically next week’s cash.
Separate collections from invoices already issued from receipts arising from future trading. For card or app sales, use the settlement timetable and account consistently for processing fees, refunds and chargebacks. If a provider deposits a net amount, do not subtract the same fee again elsewhere.
Make the receipt assumptions visible
Confirmed: supported by a payment notification or other reliable evidence, while recognising settlement can still change.
Expected: based on current orders, trading patterns and customer payment behaviour.
Uncertain: dependent on an unresolved dispute, unsigned order or other event that has not occurred.
These are planning labels, not prescribed probabilities. Document the amount, expected week, evidence and person responsible for following up. Do not add speculative sales merely because they are needed to cover an approaching payment.
Step 4: Map payments to their actual due weeks
Include cash paid to suppliers, employees and contractors, plus occupancy costs, operating expenses, tax, superannuation and existing debt repayments. Add one-off equipment purchases, repairs, insurance renewals and other commitments within the horizon.
For existing loans, include the actual repayment cash flow—not just the interest expense in the profit and loss statement. Conversely, depreciation is not a cash payment. Review recurring debits against bank records so commitments do not disappear because an invoice has not yet been entered.
Use consistent GST treatment. Where receipts and supplier payments include GST, separately include the relevant net tax settlement in its expected payment week without deducting the same GST twice. Tax balances, reporting arrangements and due dates should be validated by your accountant or registered tax adviser.
Step 5: Calculate the weekly cash position
Total receipts = all expected cash inflows for that week.
Total payments = all expected cash outflows for that week.
Net cash movement = total receipts minus total payments.
Closing cash = opening cash plus net cash movement.
Next week’s opening cash = this week’s closing cash.
Check both the lowest weekly closing balance and the payments that create it. If opening cash has already been included in these calculations, do not subtract it again when interpreting a negative low point.
Illustrative three-week extract
Assume usable opening cash of $20,000. In week one, receipts of $15,000 and payments of $30,000 leave $5,000. Week two brings in $10,000 and pays out $25,000, producing a closing balance of minus $10,000. Week three receives $35,000 and pays $20,000, returning closing cash to $5,000.
The business finishes this extract positive but still has a $10,000 low-point shortfall before uncommitted new funding. These figures are hypothetical, not a client result or borrowing recommendation. The question is what happens before week two’s payments, not whether week three looks better.
Step 6: Test a coherent downside scenario
Create an alternative case using identifiable events. Examples include a major customer paying later, lower settlement receipts during a quiet period or an essential repair costing more. Change the affected receipt and payment weeks together rather than applying an unexplained percentage to everything.
In the example, suppose $20,000 of week three’s receipts moves to week four. Week three now closes at minus $15,000, rather than plus $5,000. Record the $20,000 in week four if collection is still reasonably expected; a delay and a permanent lost receipt are different assumptions.
If the owner selects an illustrative $5,000 minimum cash buffer, the downside’s gap to that buffer is $20,000: $5,000 less minus $15,000. That is planning headroom, not an approved facility or an instruction to borrow. Operational changes, existing accessible funds and the cost and serviceability of any proposed finance require separate assessment.
A practical spreadsheet template structure
Use one column per week and keep editable assumptions separate from formulas. A straightforward template can use the following row groups:
Controls: scenario, week commencing, usable opening cash and a chosen minimum buffer.
Receipts: customer collections; cash, card and app settlements; other confirmed receipts.
Payments: suppliers and stock; wages and contractors; occupancy; operating costs; tax and super; existing debt; equipment and maintenance; withdrawals; other payments.
Outputs: total receipts, total payments, net movement, closing cash and the gap to the chosen buffer.
Assumption log: source, timing basis, responsible person and review date.
Enter zero when you have deliberately assessed an item as having no cash movement. Treat a blank or unknown amount as information still required, not automatically as zero. A zero-filled starter spreadsheet is not a completed business forecast.
The business.gov.au page linked above also provides a cash-flow statement spreadsheet that can be adapted to weekly periods. Whatever template you use, validate its formulas, tax treatment and scope before relying on the result.
Step 7: Update it as a rolling forecast
Preserve a dated copy of the forecast before replacing estimates with actuals.
Reconcile the completed week to bank movements and explain material receipt and payment differences.
Distinguish timing changes from amounts unlikely ever to be received or paid.
Refresh customer collection assumptions and upcoming commitments.
Advance the horizon and add a new final week, retaining date-specific inputs rather than merely relabelling old columns.
Assign actions for low-point weeks and review whether those actions actually happened.
For tight cash positions, review daily payment and settlement dates as well. A positive Friday balance can hide a Wednesday shortage. Frequency should reflect the business’s volatility and commitments, not the convenience of updating a spreadsheet.
How can the forecast support a finance discussion?
A finance broker can use the forecast to understand the purpose, timing and duration of a possible funding requirement and discuss potential structures. Lenders may also request accounts, bank statements, existing borrowing details and supporting evidence; requirements depend on the application.
Any proposed funding should be tested with its drawdown timing, fees and repayments included in a separate assessment. A forecast showing ongoing operating deficits needs investigation beyond a larger loan limit.
For practical examples of funding being considered alongside trading needs, the related Fairlane case studies below discuss different business cash cycles. They are specific examples, not evidence that another business will receive the same outcome.
Frequently asked questions
Should I use invoice dates or payment dates?
Use expected bank receipt and payment dates. Invoice and accounting dates help explain the transaction but do not necessarily show when cash becomes available.
Is a 13-week forecast enough for seasonal businesses?
Not necessarily. It is useful for near-term timing, but a longer forecast may be needed to capture quieter seasons, annual costs or expansion commitments.
Does a negative balance mean the company is insolvent?
A forecast shortfall is a warning requiring investigation, not a legal conclusion by itself. If company directors suspect the company cannot pay debts when due, seek qualified accounting, legal or insolvency advice promptly.
Should I count a loan that has not been approved?
Do not treat unapproved finance as available cash in the core forecast. Assess proposed funding separately, including conditions, availability, costs and repayments.
Use the forecast to identify actions, not just balances
A useful forecast connects evidence to dates and dates to decisions. Check the assumptions with your accountant, investigate the low-point weeks and review any remaining funding requirement on its own merits.
Related Fairlane reading: CASE STUDY: Cash Flow Solution for a High-Volume Shopify Store; CASE STUDY: Trade Finance for a Women’s Fashion Manufacturer; CASE STUDY: Funding to Grow & Protect Profits for a Furniture Business
Planning Your Business Cash Flow?
Discuss your forecast and possible funding structures.
General information only. This article does not constitute financial, credit, legal, tax, accounting, compliance or valuation advice. Finance is subject to lender approval, eligibility criteria, terms, fees and conditions. Consider obtaining independent professional advice for your circumstances before acting.
