Build Your 13-Week Cash Flow Forecast This Weekend
By Allan C. Haynes FCCA FCA CTP
Last week we put a number on what foresight is worth. This week, and for the four weeks after it, I want to hand you the tools to earn that number—one practical playbook at a time. We start with the single most useful document an owner can keep: a rolling 13-week cash flow forecast. If your profit and loss tells you whether the business is working, the 13-week forecast tells you whether it will still be standing in three months. They are not the same question, and only one of them keeps you up at night.
Why thirteen weeks?
Thirteen weeks is one quarter—far enough ahead to see a squeeze while you can still do something about it, near enough that your estimates are honest rather than fiction. A twelve-month forecast is a planning tool; a 13-week forecast is a survival instrument. It works in weeks, not months, because cash troubles rarely respect a calendar month: payroll, a big supplier run, and a slow-paying customer can collide on a Thursday and be forgotten by the month-end average.
The structure, in plain terms
Open a spreadsheet. Down the left, three blocks: cash in, cash out, and the running balance. Across the top, the next thirteen weeks by their start date. It really is that simple.
- Opening balance. This week's actual bank balance—the real one, across every account. Everything hangs off this figure, so get it right.
- Cash in. Not sales—collections. Walk your receivables list and place each expected payment in the week you honestly expect it to land, based on how that customer actually pays, not their stated terms. Add other inflows: loans, refunds, owner injections.
- Cash out. Every payment leaving the account: supplier bills by their real payment date, payroll on its dates, rent, loan repayments, tax, VAT, the direct debits everyone forgets. Be generous here; understating outflows is how forecasts lie.
- Closing balance. Opening + in − out. That figure becomes next week's opening. Copy it across all thirteen weeks.
Now read what it tells you
The magic is in the closing-balance row. Scan it left to right. Any week that dips toward zero—or below—is a warning lit weeks in advance. A negative in week nine, spotted today, is a manageable conversation: pull a collection forward, delay a discretionary payment, arrange a small facility calmly. The same negative discovered in week nine itself is a crisis. Same number, entirely different life. This is the whole point of foresight made concrete.
The habit that makes it powerful
A forecast built once and filed is worthless. The discipline is to roll it: every Monday morning, drop the week that has passed, add a new week thirteen out, and—this is the part that teaches you—replace your estimates for the current week with what actually happened. Within a month you will see exactly where you are optimistic (almost always on collections) and start forecasting like a treasurer instead of a hopeful owner.
The honest catch
Done by hand, this is perhaps an hour on a Monday—not onerous, but it depends on two things we have discussed: books current enough to trust (Week 6) and a real read on how each customer pays (Week 7). Do it manually for a month or two and you will feel both the value and the friction. The value is why the tool matters; the friction is why automating it matters even more.
Your one action this week: build the thirteen columns and fill in just the next four weeks. Even a month of visibility beats none, and you will almost certainly spot something you would rather have seen than been surprised by.
CrediPulse AI builds and rolls this forecast for you automatically—learning how your customers actually pay and updating with every invoice and bill. It launches Tuesday 20 October 2026, with plans from US$19 a month; waitlist members get first access and a Founders' Circle invitation (30% off year one, 100 places, through 31 October).
Part of the Money Moves Forward series by ACH Consulting Inc. CrediPulse AI launches 20 October 2026 — join the early-access waitlist at ach-consultinginc.com.