Cash Flow: The Number That Kills Companies

You can be profitable on paper and still miss payroll on Friday. That gap, between the profit your accountant reports and the money actually sitting in the bank, is what puts otherwise healthy companies into the ground. It rarely announces itself. One month you are fine, the next you are ringing a supplier to beg for another two weeks, and you cannot work out how it happened because sales were up.

Profit is an opinion shaped by accounting rules. Cash is a fact you can check on your banking app. The two move on different clocks, and the distance between them is where founders get ambushed.

Why profit and cash pull apart

Your profit and loss statement records a sale the moment you raise the invoice. Your bank account records it when the customer actually pays, which might be sixty days later, or ninety, or after three chasing emails and a phone call. In between, you have paid your staff, your rent, and your suppliers. The profit is real. The cash to fund the wait is your problem.

Growth makes this worse, not better. This is the part that catches people out. When you grow, you buy more stock and take on more staff before the extra revenue lands. So the faster you grow, the more cash you consume up front, and a fast-growing company can starve itself while every chart points up and to the right. If you want the deeper mechanics of what each customer costs you to serve and fund, that sits in unit economics.

Take a worked example. Meridian Joinery is a bespoke kitchen fitter with eight staff. In March they win a run of new contracts and bill £120,000 for the month, up from their usual £70,000. On paper March is their best month ever. But the timber, the hardware, and the subcontracted stone all get paid within thirty days, and their trade customers pay on sixty-day terms. So in March they lay out roughly £68,000 in materials and wages against those jobs, and the £120,000 does not arrive until May. Meanwhile April's jobs need funding too. Their profit is climbing while their bank balance drains toward zero. Nothing is wrong with the business. Everything is wrong with the timing.

The thirteen-week forecast

The single tool that prevents most cash deaths is a rolling thirteen-week cash forecast. Not an annual budget. A week-by-week map of money in and money out for the next quarter, updated every Friday.

Thirteen weeks is the sweet spot. It is far enough ahead to give you room to act, since most cash problems can be softened if you see them six or eight weeks out, and short enough that your estimates are grounded in real invoices and real bills rather than guesses. Build it in a spreadsheet. Do not buy software for this yet.

Set it up with columns for each of the next thirteen weeks. Down the side, list your opening bank balance, then every expected receipt, then every expected payment, then the closing balance that carries into the next week. The receipts come from your outstanding invoices dated by when customers realistically pay, not when terms say they should. If a customer always pays at seventy days despite thirty-day terms, model seventy. The payments come from payroll dates, rent, VAT, tax, loan repayments, and supplier bills you already know are coming.

The closing balance line is the whole point. Read across it. The week it dips near zero or goes negative is the week you need to have already fixed, and now you have two months to do it instead of two days.

Here is Meridian's forecast doing its job. In late January their forecast shows the closing balance for the week of 5 May dropping to minus £14,000 because of the March timing crunch. They see it in January. That gives them options that cost almost nothing: ask the biggest March customer for a 40% deposit, delay a van purchase from April to June, and agree an overdraft with the bank while the numbers still look strong. Any one of those closes the gap. Spotted in May, none of them are available, and the only option left is an emergency loan at a punishing rate or a missed payroll.

The levers that actually move cash

When the forecast shows trouble, you have a handful of real levers. Pulling them is uncomfortable, which is why people wait too long.

Speed up money coming in. Invoice the day the work is done, not at month end, because a bill raised on the 2nd and one raised on the 30th both get paid on the same customer clock, so the later one just costs you four weeks. Take deposits on large orders. Offer a small discount for fast payment only if the maths works, and it usually does not, so run it before you commit. Chase overdue invoices the day they go overdue, politely and by phone. The full playbook for this lives in getting paid.

Slow down money going out, within reason. Pay suppliers on the terms they give you rather than early. Move large one-off purchases to months where the forecast shows a cushion. Ask suppliers for longer terms before you are desperate, because a supplier will extend thirty days to sixty for a good customer who asks calmly, and will not for one who is clearly drowning.

The one lever people reach for first is usually the worst: cutting prices to win cash-generating volume. That accelerates the treadmill. More low-margin work means more materials and wages to fund up front for thinner reward. If cash is the problem, higher deposits beat lower prices almost every time.

Know your runway and your buffer

Two numbers should live in your head at all times.

Your cash buffer is how many weeks of total outgoings you hold in the bank right now. Add up a normal month's payments, divide by four to get a weekly figure, then divide your bank balance by that. If Meridian spends £84,000 a month, that is £21,000 a week, and a £42,000 balance is a two-week buffer. Two weeks is dangerously thin for a business with sixty-day receivables. Six to eight weeks is a sensible floor for most small firms. Businesses with lumpy, project-based income need more.

Your burn, if you are pre-profit or investing hard, is how much cash you consume in a month after all receipts. Divide your bank balance by your monthly burn and you get your runway in months. A startup with £180,000 in the bank burning £30,000 a month has six months of runway, and month six is not when you start fundraising. Month three is, because raising money takes longer than you think and a visible deadline weakens your hand at the table.

Where this goes wrong

The most common failure is building the forecast once, feeling reassured, and never touching it again. A cash forecast is only useful updated. Reality diverges from the plan within a fortnight, a big customer slips a payment, a bill comes in higher, and a stale forecast is worse than none because it gives false comfort. Block thirty minutes every Friday. Update actuals, roll the window forward one week, and look hard at any closing balance under your buffer.

The second failure is optimism in the receipts column. Founders model customers paying on terms because that is what the contract says. Your history knows better. Pull last year's actual payment dates and use the real average, and if a customer has never once paid inside forty-five days, stop pretending this invoice will be different.

The third is treating VAT and tax as if the money were yours. That £30,000 of VAT sitting in your account is not working capital. It belongs to the taxman and it leaves on a fixed date. Founders who dip into it to cover a wobble create a bigger, harder-dated hole one quarter later. Keep a separate savings account and sweep the VAT and tax portion of every payment into it the day it lands, so the balance you forecast against is genuinely yours to spend.

There is a quieter failure too: seeing the problem clearly and doing nothing because acting means an awkward conversation. Asking a customer for a deposit, telling a supplier you need longer, walking into the bank before you need to. The forecast only saves you if you use its warning to have those conversations early, while you still look like a strong business making a sensible request rather than a weak one making a plea.

Start here

Open a spreadsheet today and build thirteen columns for the next thirteen weeks. Put your current bank balance at the top of column one. Then list every payment you already know is coming, because those you know with near certainty, and add the invoices you expect to collect dated by when customers really pay. It will be rough and that is fine. The rough version done this afternoon will still show you the week that bites, and seeing that week early is the whole game.