How to Build a 13 Week Cash Flow Forecast for a Small Business

What the forecast should show

A 13 week forecast provides a short, rolling view of liquidity. It begins with cash available at the start of the first week, adds cash expected to be received, subtracts payments expected to clear, and calculates the ending balance. That ending balance becomes the next week's opening balance. The purpose is to identify timing pressure early enough for management to respond.

This forecast is not the same as a profit and loss statement. A sale can be recorded before a customer pays, and an expense can be recognized before cash leaves the account. Loan proceeds, principal repayments, tax remittances, equipment purchases, and owner transactions may also affect cash differently from reported profit. Use actual expected banking dates and label uncertain amounts rather than treating an invoice date as a payment date.

• Accounts payable and receivable explained

Build the first version from reliable records

Start with reconciled bank balances and a complete list of accounts. Review receivables by customer and use a realistic collection date based on terms, disputes, and payment history. Review payables by due date, then add obligations that may not appear in payables, such as payroll, source deductions, GST/HST, corporate tax instalments, debt service, rent, subscriptions, and planned capital purchases.

Create a base case first. Then add a clearly labelled downside case for material uncertainties, such as slower collections, lower sales, a delayed project, or an unexpected repair. A scenario is useful only when the assumption and the management response are visible. Do not use unsupported optimism to force a positive ending balance.

• Confirm every bank and credit facility balance before week one.
• List cash receipts by expected collection date, not invoice date alone.
• Capture payroll, tax, debt, supplier, and recurring obligations even when no bill has arrived.
• Separate committed, probable, and optional payments where the distinction helps a decision.
• Document the source and owner of every material assumption.
• Test formulas and trace a sample of totals back to records before relying on the result.

Turn the schedule into a weekly management habit

At the start of each week, replace the completed week's estimates with actual cash movement, explain the largest differences, and add a new thirteenth week. Repeated collection delays, cost overruns, or missed obligations are management signals, not spreadsheet noise. Assign follow up actions and carry them into the next review.

The forecast should support a decision before cash becomes critical. Possible responses may include accelerating billing, resolving disputed invoices, changing purchase timing, reducing optional spending, discussing financing early, or revising the operating plan. These choices depend on contracts, tax obligations, employment responsibilities, and the business's facts; a cash forecast does not authorize management to defer a legal obligation.