Cash flow: the only math that keeps a business alive

Revenue is vanity, profit is sanity, cash is reality. You can run a profitable business and still go broke — if the money arrives three months after the bills do. This lesson explains the difference between profit and cash, and walks through the one tool that prevents the classic small-business failure: the 13-week cash forecast.

Profit is an opinion. Cash is a fact.

Accounting profit spreads income and costs across the months they 'belong' to. Your bank balance does not. A $12,000 invoice booked this month still buys nothing until the client actually pays — and if they pay in 60 days, that's two rent cycles, two payroll runs, and a tax installment funded from somewhere else.

The reverse also happens: a business can be unprofitable for a quarter and survive comfortably if cash is arriving — which is why fast-growing companies sometimes feel rich while dying, and slow-but-steady businesses feel broke while thriving.

Build the 13-week forecast

Thirteen weeks is one quarter — long enough to see problems coming, short enough that your guesses are still educated guesses and not fiction. You need exactly three columns per week: money in, money out, and the running balance.

Week 3 in that example is the whole point: the balance doesn't hit zero, but $600 with a $6,900 tax bill already paid means one slow client puts you under. You can see that coming ten weeks out — when it's a scheduling problem and not an emergency.

• Money in — only count invoices you realistically expect to be paid. 'Signed but not delivered' doesn't count. 'Habitually pays in 45 days' means put it in week 7, not week 2.
• Money out — include everything: payroll and its taxes, rent, software, insurance, loan payments, and the quarterly tax estimate people always forget.
• Running balance — the number you'll actually check every Monday morning.

The three levers you control

When the forecast shows a squeeze, you have exactly three levers: bring money in faster, push money out slower, or hold more of a buffer. Everything else is a variation.

• Bring it in faster: deposits at booking, shorter payment terms, discounts for early payment, invoice the day the work ships — not the end of the month.
• Push it out slower: negotiate longer terms with your two or three biggest suppliers before you need them. It's a five-minute ask when times are good and impossible when they're not.
• Hold a buffer: the boring one. A reserve account covering 4–8 weeks of fixed costs turns most 'crises' back into scheduling problems.

Common timing traps

Some cash surprises are structural. Watch for: seasonal revenue dips that your fixed costs ignore, annual insurance or license renewals landing in one lump, growth that requires you to pay for materials and labor weeks before the client pays you, and the tax payments that always feel sudden because they're quarterly.

The cheapest money in your business is the money you already have, arriving slightly sooner.

The JK23 Ledger Letter, issue 1

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