13-Week Cash Flow Forecast for Small Businesses

Free prompt: build a 13-week cash forecast with Claude

This is the prompt from the video. Attach three files (your bank balance and rules, your A/R aging, and your recurring bills), fill in the start date, and paste it into Claude. Then check the answer: opening cash matches the bank, every bill lands in the right week, and the lowest week makes sense.

You are helping a small business owner build a 13-week cash flow forecast.
Attached: our bank balance and rules, A/R aging, and recurring bills.

Build a weekly table, Monday start, for 13 weeks beginning [date].
Rows: opening cash, cash in (by source), cash out (by bill), net change, ending cash.
Rules:
- Start from the opening bank balance exactly.
- Collections follow how customers actually pay (see notes), not invoice terms.
- Leave out anything marked "assume none".
- Put each bill in the week its due date falls in.
- Flag any week where ending cash is below our minimum cash rule.

Then: list your assumptions, name the lowest week and why, and suggest
three ways to fix it. Ask me if anything is unclear instead of guessing.

Free template and example inputs

The finished forecast from the video, built for a fictional Houston HVAC company, Gulf Coast Comfort Services. Blue cells are inputs: swap in your own numbers and the weekly table updates.

All demo data is fictional. Use the CSVs to practice the prompt before you try it on your own numbers.

The short answer: a 13-week cash forecast is a weekly projection of cash in and cash out for the next quarter. It starts from your real bank balance, uses your receivables, bills, and payroll, and is updated every week, so you see a cash crunch weeks before it hits instead of the day it does.

Profit isn’t cash

Most owner-operated businesses that run out of cash were profitable on paper. A big job front-loads labor and materials, the customer pays in 60 days, payroll lands on a Friday, and the P&L never warned you. A 13-week forecast is how you see that coming.

Can we make payroll in week 9? The forecast should answer that in one glance.

What goes into a Kalos 13-week cash forecast

Opening cash: your actual bank balances, not the book balance
Collections: expected customer payments by week, from your AR aging and real payment habits
Payroll: every pay date, with taxes
Bills and fixed costs: vendors by due date, rent, insurance, loan payments, credit card payoffs
One-offs: equipment, tax payments, owner distributions
Cash floor: the minimum balance you never want to go below, and the weeks that break it

The weekly rhythm

Each week the forecast rolls forward. Last week’s forecast gets compared to actual, the variance gets explained, and the next 13 weeks get updated. After a month, the forecast gets accurate enough to make decisions with: when to buy the truck, when to draw on the line, which customer to call first.

What you decide with it

Whether you can afford a hire or a piece of equipment, and when
Which late invoices matter most this week
When to talk to the bank, before you need to
How much you can safely distribute to owners

The 13-week forecast is part of Compass

Kalos runs the forecast weekly in Compass, the fractional CFO tier, from $7,000 per month. It depends on clean books and current AP/AR, which is why Compass includes Ledger and Rhythm. Rhythm on its own includes a weekly cash position and a four-week payment plan.

13-week cash forecast: common questions

What is a 13-week cash flow forecast?

A week-by-week projection of cash in and cash out for the next 13 weeks, about one quarter. It starts from your actual bank balance and is built from receivables, bills, payroll, and known one-off payments, so it shows the weeks where cash gets tight before they arrive.

Why 13 weeks?

It’s long enough to see a problem coming and do something about it (collect faster, delay a purchase, draw on the line), and short enough to forecast with real data instead of guesses. Banks and turnaround advisors use the same horizon.

How is a 13-week forecast different from a budget?

A budget is a monthly plan for profit over a year. A 13-week forecast is weekly and about cash. You can be profitable on the budget and still miss payroll in week 9 because a big customer paid late.

How often should it be updated?

Weekly. Each week, roll forward one week, replace the forecast with actuals, and compare. The variance is where you learn what’s actually driving cash.

Can I build one in Excel?

Yes. Start with your bank balance, list expected collections by week from your AR aging, list payroll, rent, debt, and bills by due date, and set a minimum cash floor. The hard part isn’t the spreadsheet, it’s keeping it honest every week.

Does Kalos build 13-week cash forecasts?

Yes. It’s part of Compass, the Kalos fractional CFO tier, from $7,000 per month. Kalos builds the model, updates it weekly from QuickBooks Online and Ramp, and walks you through it in a weekly meeting.

The 13-week cash forecast: see the cash crunch before it hits.

Watch: How to Build a 13-Week Cash Flow Forecast with Claude (CPA Walkthrough)