A full sales pipeline does not tell you whether next month's payroll is covered. For a service business, the timing of customer receipts can matter as much as the amount invoiced. A 13-week cash flow forecast makes that timing visible in a manageable weekly view.

This is a forward-looking management tool. It tracks expected bank movements rather than replacing your accounting records. BDC's cash planning guidance also describes the value of a rolling 13-week forecast updated weekly.

1. Build the weekly structure

Use one column for each week and rows for opening cash, customer receipts, other inflows, payments and closing cash. Start with reconciled balances in the accounts included in the forecast. Show restricted funds separately so they are not mistaken for cash available to spend.

Closing cash = opening cash + cash received − cash paid. The closing balance of one week becomes the opening balance of the next. Keep transfers between included bank accounts out of total external receipts and payments to avoid double counting.

2. Forecast receipts by expected payment date

List outstanding invoices with customer, amount, due date, expected receipt date and the person responsible for collection. A due date is not always a realistic receipt date. Keep signed work separate from unconfirmed opportunities and explain any assumptions about deposits or staged payments.

For different currencies, keep a currency column and an explicit conversion assumption. Do not add amounts in different currencies together as though they were equivalent.

3. Add payments that can actually reach the bank

Include payroll, suppliers, rent, software, tax payments, debt repayments and planned equipment purchases. Use the expected payment date. Confirm tax amounts and deadlines with your accountant rather than applying a generic percentage.

Give uncertain items a note and an owner. This makes it possible to update the forecast without guessing what the previous author intended.

4. Test one delayed receipt

Here is an illustrative example, not a client result. Opening cash is €24,000, expected receipts are €18,000 and payments total €31,000. The forecast closes at €11,000. If a €12,000 receipt moves to the following week, the closing balance becomes −€1,000.

The commercial value of the sale has not changed, but the timing creates a financing gap. The forecast gives you a reason to discuss collections, planned spending or funding before that week arrives. It does not justify missing agreed payment obligations.

5. Make the update routine small

• Replace the completed week's forecast with actual bank movements.
• Explain material differences in timing or amount.
• Review outstanding receipts with their owners.
• Add a new thirteenth week and save a dated version.
• Record decisions, owners and follow-up dates.

Protect formula cells from accidental edits, but remember that range protection is not a confidentiality control; Google explains its limitations. Control access to the file itself.

Need a forecast connected to your reporting and payment calendar? Explore Finance Therapy's budgeting and payment calendar tools or book a call to discuss your current process.