Entrepreneurship field guide

How to Build a Simple 13-Week Cash Flow Forecast

A 13-week cash-flow forecast gives a small business a near-term view of when money is expected to arrive, when obligations must be paid, and where a shortfall may develop before the bank balance reveals it.

Why thirteen weeks is useful

Thirteen weeks is long enough to expose payroll, rent, supplier, tax, debt, and collection patterns while remaining close enough for detailed estimates. It does not replace an annual budget or financial statements. It supports short-term liquidity decisions.

Profit and cash differ. Revenue may be recognized before payment arrives. Inventory or annual expenses may consume cash before they affect reported profit. A profitable business can face a cash crisis when timing is poorly managed.

Start with verified opening cash

Use the available bank balance at the beginning of week one, adjusted for payments or deposits that have not cleared. Separate restricted funds or money reserved for obligations where appropriate. Do not count unused credit as cash.

If the business uses several accounts, create a consolidated view while preserving any legal or operational restrictions. Reconcile the starting figure so the forecast begins from reality rather than an old spreadsheet.

Forecast receipts by collection date

List invoices and expected payment weeks based on terms and customer behavior. Separate contracted recurring revenue, issued invoices, highly likely sales, and speculative pipeline. The forecast should make uncertainty visible rather than combining every possibility into one total.

For card or marketplace receipts, account for payout delay, fees, reserves, and refunds. For deposits and milestone billing, connect the date to the actual contract and delivery plan. Update when customer circumstances change.

List outflows completely

Include payroll, contractors, suppliers, rent, software, insurance, loan payments, tax, inventory, marketing commitments, refunds, owner draws, equipment, and one-time expenses. Identify which payments are fixed, variable, discretionary, or legally restricted.

Timing matters. Annual renewals and quarterly tax payments can disappear from a monthly mental model. Review prior bank statements, accounting records, contracts, and calendars to catch them. Ask a qualified accountant about reporting and tax treatment.

Calculate weekly movement

The closing balance becomes the next week’s opening balance. Add a minimum operating threshold appropriate to the business. Highlight any week that falls below it.

Use scenarios for important uncertainty

Create a base case using the most defensible assumptions. Add a downside case for delayed receipts, lower sales, or higher cost. Use an upside case cautiously; it should not justify commitments that the base case cannot support.

Scenarios are most useful when they trigger decisions. Define what happens if a major invoice moves two weeks, demand slows, or a supplier requires earlier payment. The response might include collecting deposits, delaying discretionary spending, changing purchasing, discussing terms, or arranging finance before the need becomes urgent.

Update actuals every week

Replace forecast numbers with actual receipts and payments. Move late items rather than leaving them in the past. Record the reason for material differences. Over time, the forecast reveals patterns in customer payment, sales assumptions, project delays, and expense timing.

Assign one owner and a consistent review time. Include people responsible for sales, delivery, and spending so the forecast reflects operational knowledge. Restrict access appropriately because cash information is sensitive.

Frequently asked questions