A 13-week cash-flow forecast is not a smaller annual budget. It is a short-horizon operating instrument built around the expected clearing date of cash receipts and payments.
Why thirteen weeks?
Thirteen weeks is long enough to see a quarter of payroll, tax, debt, supplier and customer timing, but short enough for management to challenge individual movements. It converts a general concern about liquidity into a dated decision: the week a buffer is threatened, the size of the gap and the lead time available to respond.
1. Set the opening position and minimum buffer
Start with reconciled cash available at the beginning of the first week. Exclude undrawn facilities unless the forecast explicitly models a permitted draw. Then set a deliberate minimum cash buffer. The buffer is not zero; it is the amount management wants available for operational uncertainty, payment timing and commitments that cannot be deferred safely.
If opening cash is already below the buffer, record an immediate breach. A receipt expected later in week one does not remove the opening funding need.
2. Forecast receipts when cash is expected to clear
List material customer receipts, recurring income, asset proceeds, funding and other inflows. Use the week cash is expected in the bank—not the invoice date, revenue-recognition date or contractual due date. Separate large or uncertain receipts so management can challenge them individually.
3. Forecast payments by operational commitment
Map payroll, tax, rent, suppliers, debt service, capital expenditure and other payments to the week they are expected to clear. Keep unavoidable commitments visible. A stress scenario is useful only when it does not quietly remove costs that management cannot actually avoid.
4. Roll cash forward every week
The calculation is simple: opening cash plus receipts less payments equals closing cash. The following week opens with the prior week's closing cash. The discipline lies in timing, completeness and reconciliation—not complicated mathematics.
Illustrative worked example
These figures are examples only. Assume a business opens week one with 250,000 in cash and sets a 100,000 minimum buffer:
- Week 1: 250,000 opening cash + 120,000 receipts − 180,000 payments = 190,000 closing cash.
- Week 2: 190,000 opening cash + 95,000 receipts − 150,000 payments = 135,000 closing cash.
- Week 3: receipts were expected to be 120,000, but a 75,000 customer receipt moves to a later week. With 45,000 of other receipts and 110,000 of payments, closing cash is 135,000 + 45,000 − 110,000 = 70,000.
The week-three closing balance is 30,000 below the stated buffer (100,000 − 70,000). That is a funding gap against the chosen buffer, even though the bank balance remains positive. If the delayed receipt has a realistic two-week lead time, management needs to decide before the breach whether to accelerate collection, renegotiate a supplier payment, defer discretionary expenditure or arrange committed funding.
5. Build scenarios from named assumptions
A base case should represent management's most supportable view. An upside case may accelerate a specific receipt or improve a known commercial outcome. A downside case may delay collections, increase a payment or preserve uncertainty. Scenarios should identify the movement changed, its base timing and the revised timing or amount. A label alone is not evidence.
Sometimes an item is cancelled or deferred beyond the horizon. Record that disposition explicitly rather than hiding it in a zero or a fictional week fourteen. If upside and downside paths cross, investigate why rather than forcing the labels to look orderly.
6. Update actuals and explain variance
At the end of each week, reconcile the actual closing bank position. Replace forecast movements with actual movements for completed weeks, roll the new opening position forward and explain the largest timing and amount variances. A forecast that is not reconciled becomes a spreadsheet narrative rather than a cash control.
The weekly management questions
- What changed since last week?
- Which receipt or payment drives the lowest cash point?
- When is the first buffer breach, including the opening position?
- What action must be completed before that week?
- Who owns the action and what evidence will confirm it?
When a cash forecast points to a wider funding or governance decision, Executive Compass Advisory describes the available executive finance and board decision support.
Use the free worked tool
The Executive Compass Cash Command Centre builds a 13-week forecast in your browser, tests base, upside and stress timing, identifies the funding gap and exports an Excel workbook. Detailed financial inputs stay in the browser and are not submitted to Executive Compass.
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