A thirteen-week cash flow forecast projects the cash a business expects to receive and pay each week for roughly the next three months, starting from today's actual balance. Because it works in weeks rather than months, it shows timing problems that monthly budgets hide, such as a payroll week that falls before a large customer payment.
A reliable thirteen-week view is built from open receivables and payables, payroll schedules, debt payments, taxes, and explicit assumptions about when customers will pay. It is updated weekly, and the previous week's forecast is compared with what actually happened to improve the assumptions. Lenders, turnaround advisers, and owners of seasonal businesses rely on it heavily.
Example
A contractor sees that week seven combines two payrolls, a materials order, and a delayed owner draw, and arranges a short-term draw on its line of credit three weeks in advance.