CASH FLOW
Most SME owners know their bank balance to the pound. Far fewer know their cash runway: the number of months the business could keep operating at its current rate of spending before the cash runs out. This is a dangerous gap, because a business can look healthy on paper and still be weeks away from serious trouble.
Optimising cash runway is not about panic or crisis management. It is about building a simple, repeatable framework that gives you early warning and real control.
Why Cash Runway Matters More Than Your Bank Balance
Cash runway is calculated in a simple way: take your current cash balance and divide it by your average monthly cash burn (the amount your outflows exceed your inflows each month). The result tells you how many months of breathing room you have if nothing changes.
Here is the trap many SME owners fall into. The profit and loss account shows a profitable month, so everything feels fine. But profit is an accounting figure, not a cash figure. A business can be profitable and still run out of cash, because of unpaid invoices sitting on the sales ledger, stock tied up in the warehouse, or a large tax bill due next quarter. Profit measures what you have earned. Runway measures what you can actually spend.
This is why cash runway deserves its own regular check, separate from the profit and loss review. The framework below gives you a structured way to do that check and, more importantly, to act on what you find.
The Cash Runway Framework — Three Levers You Can Pull
Think of your business finances like a bath. Water flows in through the taps. Water flows out through the plughole. And the speed at which the water level rises or falls depends not just on the taps and the plughole, but on the timing: how much water is going in and out at any given moment.
Cash runway works the same way, through three levers:
Inflows — the taps. How much cash is coming into the business, and how quickly.
Outflows — the plughole. How much cash is leaving the business, and on what.
Timing — the gap between the two. When cash actually arrives compared with when it actually leaves.
Most SME owners instinctively reach for only one lever, usually outflows, and start cutting costs. This can help, but it is only a third of the picture. A stronger approach pulls all three levers together, because a small improvement in each one compounds into a much bigger effect on runway overall.
Lever One — Increasing Inflows
The most direct way to extend runway is to bring cash in faster and in greater volume. A few practical starting points:
Speed up collections. Invoice as soon as work is delivered, not at the end of the month as a batch. Shorten payment terms where you reasonably can, and consider asking for a deposit upfront on larger projects.
Review pricing, not just volume. Many SME owners assume the only way to increase cash inflow is to win more customers. Often a modest, well-justified price increase on existing work has a faster and larger effect, without the cost of winning new business.
Identify your fastest-cash customers and services. Not every profitable line of work generates cash at the same speed. A service with slower payment terms may look attractive on the profit and loss account but drag on runway. Knowing which customers and services convert to cash quickest lets you make better decisions about where to focus effort.
Lever Two — Controlling Outflows
The second lever is spending discipline, but applied with judgement rather than a blanket cut.
Separate essential spend from discretionary spend. Payroll, rent, and supplier payments that keep the business running are essential. Software subscriptions you rarely use, or discretionary marketing spend with no clear return, are discretionary. Review the discretionary list first.
Renegotiate terms, not just prices. Suppliers are often willing to extend payment terms, especially for long-standing relationships. This does not reduce your total spend, but it does improve your runway by delaying the outflow.
Avoid the false economy. The most common mistake here is cutting costs that damage future revenue, such as reducing marketing spend to zero, or delaying essential equipment maintenance. This can protect cash in the short term while quietly shortening runway further down the line, because inflows fall as a result. Every cost cut should be tested against this question: will this reduce inflows more than it reduces outflows?
Lever Three — Managing Timing
Many SME owners assume their runway problem is a totals problem: not enough coming in, too much going out. Often the real problem is timing: the gap between when cash leaves the business and when it arrives.
Build a rolling 13-week cash flow forecast. This is the single most useful tool for spotting timing gaps before they become a crisis. It gives you visibility of specific weeks where outflows will exceed inflows, rather than a vague monthly average.
Stagger large payments. If a large supplier payment and a large payroll run fall in the same week, the business can look short of cash even if the month as a whole is fine. Spreading large payments across the month smooths this out.
Align payment terms where possible. If customers pay you on 60-day terms but you pay suppliers on 30-day terms, you are effectively funding that 30-day gap yourself. Bringing these terms closer together reduces how much working capital your business needs to hold.
Bringing the Three Levers Together — A Simple Worked Example
Consider an SME with a monthly cash burn of £10,000 and a cash balance of £40,000. On its own, that gives a runway of four months.
Now apply all three levers together:
Inflows — tightening payment terms and adding a deposit requirement brings in an extra £2,000 a month in cash.
Outflows — cutting three unused software subscriptions and renegotiating one supplier contract saves £1,500 a month.
Timing — moving a large quarterly payment to align with a stronger cash week, rather than a weaker one, avoids a short-term shortfall that would otherwise have forced the business to draw on a costly overdraft.
The combined effect is a reduction in monthly cash burn from £10,000 to £6,500. On the same £40,000 balance, runway extends from four months to over six months, without a single dramatic decision. This is the value of the framework: small, deliberate moves across all three levers, rather than one large and disruptive move on a single lever.
Building a Habit of Reviewing Your Runway
A cash runway framework only works if it is reviewed regularly, not treated as a one-off exercise.
Review monthly as a baseline. If cash is comfortable, a monthly check against your 13-week forecast is usually enough.
Review weekly if runway is under six months. At this point, small changes in timing can have an outsized effect, so more frequent visibility matters.
Ask the same three questions each time: What has changed in inflows this month? What has changed in outflows? Has the timing gap between the two widened or narrowed?
Treating cash runway as an ongoing discipline, rather than something you only think about in a crisis, is what turns this framework from a one-off fix into a lasting habit that protects the business.
TLDR: Cash runway is not one number to fear, but three levers — inflows, outflows, and timing — that an SME owner can pull deliberately, each month, to extend how long the business can operate.
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