The 13-week
cash flow forecast.

Ask most business owners about their cash position and they’ll quote the bank balance. That number is real, but it’s a photograph. It says nothing about the payroll run next Friday, the sales tax payment the week after, the insurance premium that hits quarterly, or the big customer invoice that may or may not land before all three.

A 13-week cash flow forecast turns that photograph into a film. It is a weekly projection of every dollar in and every dollar out, thirteen weeks forward, updated every week with actuals. It is the standard tool in turnaround work for a reason: it is the fastest way to see trouble while there is still time to do something about it.

Why thirteen weeks

Thirteen weeks is one quarter — long enough to see past the current month’s noise, short enough that the projections stay concrete. Beyond a quarter, you’re guessing. Inside a quarter, you know most of what’s coming: which invoices are outstanding, which bills are due, when payroll runs, when tax deposits hit. The forecast is built from knowledge, not hope.

Weekly granularity is the other half of the value. Monthly forecasts hide the problem weeks. A month can look fine in total while week two contains a payroll run, a loan payment, and a tax deposit all landing before your biggest receivable arrives. The 13-week view catches the collision. A monthly view doesn’t.

How to build one

The structure is simple. Down the left side: cash receipts by source (customer collections, other income), then cash disbursements by category (payroll and payroll taxes, rent, materials and inventory, insurance, loan payments, sales and income tax deposits, everything else). Across the top: thirteen weekly columns. The bottom row is your projected ending cash each week.

Receipts are the hard part, and the discipline is to schedule them from your actual AR aging — invoice by invoice for the big ones, with honest assumptions about when each customer really pays, not when they’re supposed to. Disbursements are mostly known: payroll is scheduled, rent is fixed, loan payments are contractual. The forecast forces you to put dates on everything.

Then, every week, you replace week one’s projections with what actually happened, roll a new week thirteen onto the end, and look at what changed. The update takes thirty minutes once the model exists. The first version takes a day. If you already run the practices in our cash flow management guide, most of the inputs are sitting in your AR and AP aging reports.

What it catches

The forecast pays for itself the first time it shows you a negative week that’s six weeks out instead of six days out. Six weeks is enough time to accelerate collections, delay a discretionary purchase, arrange a draw on the line of credit, or have a calm conversation with your banker. Six days is a crisis.

It also surfaces slower-moving truths: a business that’s growing but consuming cash faster than it produces it, a seasonal trough that’s deeper than last year, a customer whose payments are quietly stretching from 30 days to 55. These patterns are invisible in the bank balance and obvious in a rolling forecast.

Who needs one

Any business where cash timing matters — which in practice means seasonal businesses, project-based businesses with lumpy billing, businesses in or approaching a turnaround situation, and any business growing fast enough that receivables and inventory are eating the profits. If you’ve ever been profitable on paper and still sweated a payroll run, this is the tool that ends that experience.

Building and running a 13-week forecast is standard work inside a fractional CFO engagement. It is usually the first thing we build, because everything else — pricing decisions, hiring decisions, banking conversations — gets easier once you can see the next quarter one week at a time.