A 13-Week Cash Flow Forecast You Can Actually Run Your Business On

A healthy bank balance today tells you very little about the week after your next payroll, supplier run and large annual renewal. The useful question is not simply, “How much cash do we have?” It is, “What is the lowest balance we expect, when does it happen, and what can we do before then?”

A rolling 13-week cash flow forecast is a practical way to answer that question. It turns the next quarter into a sequence of weekly decisions rather than one reassuring monthly average.

The goal is not a perfect prediction. It is enough warning to make a better decision while you still have choices.

What your forecast needs to show

Start with opening cash, expected receipts and expected payments. Closing cash is opening cash plus receipts minus payments; that closing balance becomes the following period’s opening balance. This follows the basic structure in the Australian Government’s cash flow statement guide.

For this working version, use one column per week and separate receipt and payment categories underneath. Keep the summary small enough to explain in a team meeting. You should be able to point to the lowest week, the assumptions behind it and the person responsible for the next action.

Start with cash you can actually use

Choose a cut-off date and reconcile the opening balance to your bank records. Do not include an unapproved loan, a hoped-for investment or money you cannot use for operations. Where restricted cash or a committed facility matters, show it separately rather than blending it into the bank balance.

Then gather unpaid customer invoices, supplier bills, payroll timing, debt repayments, recurring subscriptions and known one-off purchases. Treat accounting records as the starting point, not the complete forecast: next month’s payroll or a planned equipment purchase may not yet appear as an unpaid bill.

Forecast the payment date, not just the invoice date

An invoice due in week three does not help fund week-two payroll. For each material receipt, record the amount, expected collection week, supporting evidence and an owner. A confirmed customer payment date deserves different treatment from a salesperson’s expectation.

For payments, work from contractual dates and actual payment schedules. Include the applicable tax and employment-related payments on the dates relevant to your business, checked with your accountant or payroll adviser. Do not treat deferring a statutory payment as an available management lever.

Be explicit about tax treatment. A bank cash forecast should reflect the amounts that will actually move. Do not combine tax-exclusive customer receipts with tax-inclusive supplier payments and assume the difference will fix itself.

A complete 13-week worked example

Illustrative example, not MagicHub customer data. The following simplified forecast starts with A$60,000. Figures in the table are A$000 and represent total cash amounts; any applicable tax cash movements are assumed to be included. The payment detail is condensed for readability, and there is no new borrowing or owner funding.

Illustrative rolling cash forecast — A$000

Period	Opening cash	Receipts	Payments	Closing cash
Week 1	60	22	25	57
Week 2	57	18	28	47
Week 3	47	35	24	58
Week 4	58	24	32	50
Week 5	50	20	26	44
Week 6	44	38	30	52
Week 7	52	25	28	49
Week 8	49	22	34	37
Week 9	37	40	29	48
Week 10	48	26	31	43
Week 11	43	28	30	41
Week 12	41	44	32	53
Week 13	53	30	33	50

The business finishes week 13 with A$50,000. However, the lowest week-end balance is A$37,000 in week eight. That is the pressure point to investigate. A comfortable quarter-end figure does not describe every week inside the quarter.

There is another important limitation: a weekly closing balance can hide a shortfall earlier in the week. Where the margin is tight, check the actual day that payroll leaves and the actual day a major receipt is expected.

Stress-test the assumption that matters most

Suppose the A$25,000 receipt in week seven moves to week nine. Nothing else changes. Week-eight closing cash falls from A$37,000 to A$12,000, before recovering when the money arrives.

Assume management has chosen an illustrative A$20,000 operating buffer for this business. The delayed-payment case falls A$8,000 below it. That is a breach of the chosen buffer, not a negative bank balance. Keeping those two concepts separate makes the discussion more precise.

Now there is a useful decision to make: confirm the customer’s payment timing, consider an agreed deposit or milestone arrangement on future work, or assess whether a discretionary purchase can move. Record only actions that are achievable, authorised and consistent with the business’s obligations.

Run a short weekly review

1. Replace the completed week with actual cash movements. Preserve the previous forecast so you can see what changed.
2. Explain the largest differences. Separate timing changes from amounts that will not be received or paid at all.
3. Roll the forecast forward. Add a new week at the end and revisit material assumptions throughout the horizon.
4. Assign the action. Give the next collection call, supplier discussion or spending decision an owner and a date.

A useful variance note is specific: “A$15,000 moved from week four to week six following the customer’s confirmation.” “Revenue was below forecast” is not enough to improve next week’s cash decision.

Avoid the most expensive forecasting mistake

Do not count the same customer money once as an unpaid invoice and again as future sales. Give receipts a clear source and move them through the forecast as the underlying record changes. A proposed deal should leave the pipeline assumption when it becomes a confirmed contract or an invoice.

The same discipline applies to payments: a supplier bill and its planned bank payment are two views of one obligation, not two costs.

Questions worth asking before you rely on the forecast

Is 13 weeks the only horizon we need?

No. Use it for near-term payment timing, and connect it to a longer-range plan for hiring, growth and investment. Our guide to three-way forecasting with Xero explains how profit, cash and the balance sheet fit together.

Should unsigned sales be included?

Show them separately from contracted or invoiced receipts, with an explicit scenario. Our sales-pipeline-to-cash guide shows why a weighted deal amount is not a payment promise.

What should happen when the forecast looks tight?

Investigate the dates and obligations, test realistic actions and seek qualified advice early where payment capacity is uncertain. A spreadsheet cannot authorise a payment delay or determine the legal position of a business.

Make the next decision visible

Build the first version with the information you have, label the uncertain items and improve it through the weekly review. The test is whether it changes a decision—not whether it contains more rows than last month.

Explore the wider planning approach: visit MagicHub, or read why profit and cash can move in different directions.

This article provides general business education, not accounting, tax, legal or financial advice. Examples are fictional and simplified. Adapt assumptions and payment obligations with your professional adviser.