Cash flow vs profit: why your invoiced revenue is not your bank balance

The first time you make a sale that gets invoiced on Net 30 terms is the first time you understand cash flow. The invoice goes out today; the work is done; on paper, you have earned the money. But the bank account does not move for 30 days. The deal closed; you cannot pay rent with it.

Profit is what you have earned. Cash flow is what is actually in the account. They are different numbers, and the gap between them — sometimes called "working capital" — is what eats most small businesses that fail. Successful, profitable, growing companies run out of money all the time, because the money they earned in March does not arrive until late April, and the salaries are due on the 1st.

The arithmetic is simple. If your customers pay 30 days late on average, and your salaries and rent are due monthly, you need at least 30 days of operating cash sitting in the account at all times — just to bridge the gap. Grow faster than that gap can stretch and you will be in cash trouble while still booking record revenue. This is why "we hit our quarterly target" can coexist with "we cannot make payroll".

The fix is not magic; it is three things. First, shorten payment terms wherever you have leverage. Net 14 instead of Net 30 means half the working capital. Second, invoice the moment the work is delivered, not at month-end — a two-week delay in invoicing is a two-week delay in cash. Third, separate "revenue" from "cash" in your reports. The P&L tells you whether the business model works; the cash-flow projection tells you whether the business survives the next 90 days.

Most accounting tools optimise for the P&L because that is what tax authorities want. Most founders should be staring at the cash-flow projection. Run a 13-week rolling cash forecast — not a precise one, just a directionally honest one — and the moment you can see the gap shrinking faster than you can fill it, you know it is time to act. Earlier than your accountant will tell you.