Thirteen Weeks of Certainty: Making Liquidity Your First Target
Photo: Francisclarke, CC BY-SA 4.0, via Wikimedia Commons
Most UK SMEs can tell you their revenue target to the nearest thousand pounds. Far fewer can say, without opening a banking app, what their cash balance will be on the last Friday of next quarter. That gap between what is measured formally and what is monitored privately is where otherwise healthy businesses come unstuck.
Revenue is an opinion formed by an invoice. Cash is a fact confirmed by a bank statement. When the two are allowed to drift apart, the consequences arrive quickly: a VAT bill landing in the same week as payroll, a large customer stretching terms from 30 to 60 days, a supplier tightening credit because the payment record has become erratic.
The remedy is not a better spreadsheet. It is a target — a rolling thirteen-week cash figure with a defined floor, reviewed weekly, and treated with the same seriousness as the sales number.
Why the thirteen-week horizon
Three months is the longest period over which most SME cash flows can be forecast with any credibility, and the shortest over which structural problems become visible. A single quarter captures one VAT return, at least three payroll runs, and the typical lag between delivering work and being paid for it.
Thirteen weeks rather than twelve is deliberate. Weekly buckets that end on the same weekday keep the forecast aligned to actual payment runs and remove the temptation to smooth figures across a month boundary. It also leaves one week of slack: if a review is missed, the horizon has not collapsed.
Setting the floor before the forecast
A cash target has two components: a minimum balance you will not go below, and a trajectory you expect to follow. Founders tend to fixate on the first and ignore the second.
The floor should be calculated, not guessed. A workable starting point is the sum of three items:
- One month of fixed operating costs — rent, salaries, software, finance payments
- The next VAT liability, held in full from the day the quarter closes
- A contingency equal to two to four weeks of variable costs
For a business with £80,000 of monthly fixed costs and a typical quarterly VAT bill of £30,000, that produces a floor somewhere between £110,000 and £125,000. Anything below it is not a buffer; it is a countdown.
Publish the floor internally. A number that lives only in the finance director's head is not a target, it is a private anxiety.
Forecasting inflows without optimism
The inflow side of the model is where most forecasts fail, and almost always in the same direction. Invoices are logged on the date they are issued rather than the date they are likely to be paid. New business is included at pipeline probability rather than at signed contract. The one customer who habitually pays late is forecast to reform.
Correct for all three. Assign every customer a payment profile based on their last four invoices, not their stated terms. Weight new business at zero until a purchase order exists. Then build a second version of the forecast — the downside case — in which your two largest debtors pay four weeks late.
If the floor survives the downside case, the target is credible. If it does not, you have found the problem early enough to act on it.
The weekly checkpoint
The discipline only holds if the review is short enough to survive a busy week. Twenty minutes, five lines, same slot every week:
- Actual closing balance against forecast
- Variance, in pounds and as a percentage
- Known commitments in the next four weeks not yet in the model
- Invoices overdue by more than fourteen days, with named owners
- Forecast closing balance for week thirteen
Any development that moves the week-thirteen figure by more than ten per cent triggers a short written note explaining why. That note becomes the audit trail which turns a forecast into a management instrument.
What the target is telling you
A cash target earns its keep by generating early warning, not by being met. Three patterns matter most.
The forecast breach. If week nine dips below the floor on current assumptions, you have roughly six weeks to respond — renegotiate terms, accelerate receivables, defer discretionary spend. Plenty of time, provided you look.
The persistent negative variance. Three consecutive weeks of forecasting above actual suggests the model is systematically optimistic and should be recalibrated downward rather than repeatedly explained away.
The concentration signal. When more than 40 per cent of forecast inflows in any four-week window rest on a single customer, the cash target is really a credit target for that customer. That is a commercial risk, not a treasury one.
Each of these is a decision prompt with a deadline attached, which is the difference between a target and a report.
Liquidity as a growth discipline
There is a persistent belief among UK founders that cash management is what you do when growth stalls. The reverse is usually true: growth consumes cash before it produces it. Every new hire, every stock purchase, every extended payment term offered to win a contract is a withdrawal against liquidity.
A thirteen-week cash target makes that trade-off explicit. It lets a business say yes to growth with a clear view of what it costs to fund, and say no to growth that would breach the floor — a considerably better outcome than discovering the constraint at the bank.
Set it this month. One floor, one forecast, one twenty-minute slot each week. Revenue tells you how big you are getting; the cash target tells you whether you will still be there when you get there.
