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What Is a 13-Week Cash Flow Forecast?

Published October 30, 2026

A 13-week cash flow forecast is a week-by-week projection of the cash that will come into and go out of a business over the next quarter. Each week ends with a projected cash balance. Read across the row and you can see, weeks in advance, when cash will run short.

Why 13 weeks

Thirteen weeks is exactly one quarter, so the forecast lines up with quarterly items like estimated tax payments and loan covenant tests. It is also about as far ahead as a company's real transactions reach. Open invoices, unpaid bills and the payroll calendar usually cover the next 30 to 90 days. Past that point a forecast stops being built from actual transactions and starts being built from assumptions.

Weekly columns matter too. A monthly forecast can show a healthy balance at month-end while hiding the payroll week in the middle when the account dipped below zero.

What goes into one

Signs your business needs one

If none of these apply and cash is steady, you probably don't need a forecast. Good bookkeeping is enough.

What makes a forecast trustworthy

A forecast is only useful if it is right often enough to act on. That means opening cash ties to the bank, receivable and payable detail ties to the general ledger, and every month the forecast is compared with what actually happened. The comparison is where the forecast gets better over time.

See our services for one-time and monthly options, or read about planning cash for a slow season.