Guide
How to create a 13-week cash flow forecast
A 13-week cash flow forecast is the simplest reliable way to see where your bank balance is heading. Here is how to build one, what to include, and how to keep it accurate every week.
Step 1: Set up 13 weekly columns
Create one column per week, starting with the current week. Label each with the week's start date. Add rows for opening cash, money in, money out, net change and ending cash.
Step 2: Enter your opening cash balance
Use today's actual balance across your operating accounts. Don't use a figure from your P&L or balance sheet; those include amounts that haven't hit the bank yet.
Step 3: Forecast receipts by expected week
List every open invoice, retainer and other expected inflow. Put each in the week you realistically expect the money, based on how that client actually pays, not the invoice due date. If a client usually pays 15 days late, plan for it.
Step 4: Forecast disbursements by week
Add payroll on its real pay dates, then rent, contractors, software, insurance, loan payments, estimated taxes and any one-off purchases. Fixed costs are easy to place; make sure irregular bills land in the right week.
Step 5: Roll the balance forward
For each week: ending cash = opening cash + receipts − disbursements. That ending cash becomes next week's opening cash. Thirteen columns later, you have a full quarter.
Step 6: Find the low point and set a reserve floor
The single most useful number in the forecast is the lowest ending balance and the week it happens. Decide on a reserve floor — a minimum balance you don't want to go below — and highlight any week under it.
Step 7: Test the decisions you're facing
Move your largest invoice a few weeks later. Add the hire you're considering. Remove a client. Each scenario shows whether the low point stays above your floor. This is where a forecast turns into decisions.
Step 8: Update it every week
Each Monday, replace the forecast balance with the real one, mark what was paid, move anything that slipped and add a new week 13 at the end. A forecast that isn't updated stops being useful within a few weeks.
Avoid these
Common 13-week forecast mistakes
Using due dates instead of expected dates
Clients pay when they pay. Forecast from their history, not your invoice terms.
Mixing profit with cash
Depreciation, accruals and unbilled work don't belong in a cash forecast. Only money that moves through the bank.
Forgetting irregular payments
Quarterly taxes, annual renewals and insurance premiums cause most surprise low points.
Building it once
The value comes from the weekly roll-forward and the comparison of forecast to actual.
Common questions
What goes into a 13-week cash flow forecast?
An opening cash balance, expected receipts (client payments, retainers, other income) and expected disbursements (payroll, rent, vendors, taxes, debt payments) for each of the next 13 weeks.
Is a 13-week forecast the same as a budget?
No. A budget plans income and expenses, usually monthly and on an accrual basis. A 13-week forecast tracks actual cash timing week by week.
How accurate is a 13-week cash flow forecast?
It is only as accurate as the dates and amounts you enter. Accuracy improves when you compare each week's forecast to the actual balance and adjust your assumptions.
Can I build one in Excel or Google Sheets?
Yes. You can build it from scratch using the steps on this page, or start from a ready-made template such as Cash Command OS Complete.
See your own 13 weeks
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