Playbook12 min readFocus · August

13-Week Cash Flow Forecast

A working model and the weekly ritual that keeps it honest.

Focus for August

Set up Q4 ahead of time

August is when smart operators forecast the busy season instead of reacting to it.

Refreshes on the 1st of every month

Sketch out the cash needs for inventory, marketing, and seasonal payroll between September and December. Front-load the big purchases into your model now so the lender call in October is a formality.

Estimate Q4 inventory or COGS pre-buy
Pre-book any seasonal advertising commitments
Identify the week peak working capital needed
Have the lender conversation by Sept 15

Why 13 weeks

Far enough out to see the cliff, close enough to actually do something about it.

Most owner-operator failures aren't bad businesses — they're cash-timing surprises. A rolling 13-week forecast turns surprises into decisions you make on Monday morning instead of crises you react to on Friday afternoon.

What to model — line by line

Be specific. 'Other expenses: $5,000' is where forecasts go to die.

Build your weekly model with these rows. Most fit on a single screen.

Row	Source	Notes
Starting cash	Bank balance Monday AM	All operating accounts combined
Receipts — by customer	AR aging + booked deals	List top 10 customers individually
Other receipts	Refunds, deposits, financing draws	Anything non-customer
Payroll	Run dates, not pay-period end	Include employer taxes
Recurring AP	Rent, software, insurance, utilities	Group by week paid
Variable AP	COGS, subcontractors, project costs	Tie to revenue if possible
Sales tax / 941	Filing calendar	These ruin forecasts when missed
Owner draws / distributions	Your policy	Treat like a fixed cost
Debt service	Loan amortization	Principal + interest separately
Ending cash	Calculated	This is the number that matters

The weekly ritual

The discipline is the point — not the spreadsheet.

Every Monday morning, roll the model forward one week (drop last week, add a new week 13).
Update starting cash to today's actual bank balance.
Compare last week's forecast to actuals. Calculate variance for receipts and AP separately.
Any variance over 10% gets a one-sentence written reason in the model.
Update the next 4 weeks based on what you learned. Don't re-touch weeks 5-13 unless something material changed.
Send a 3-line summary to your bookkeeper or controller: cash today, cash 4 weeks out, biggest risk.

Using it with your bank

Bankers fund forecasts they trust, not stories they hope for. Bring this model to every line-of-credit conversation.

Show 8 weeks of forecast-vs-actual history (proves the model works)
Highlight the trough week and what you do about it
Tie the line-of-credit ask to a specific gap in a specific week
Show how the line gets paid down within the 13-week window

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