Why Profitable UK Businesses Still Run Out of Cash — and How to Stop It
Your P&L says you're doing well. Your bank account disagrees. Here's why, and what to do about it.
Cash flow problems kill more UK small businesses than bad products or weak sales. The Office for National Statistics data consistently shows that around 60% of businesses that fail were actually profitable at the time they closed. They ran out of cash, not out of customers.
This isn't a contradiction. Profit and cash are different things, and the gap between them is where most SME owners get caught out.
Why Profit Doesn't Equal Cash
Your P&L records revenue when you invoice, not when you're paid. It records a cost when goods are received or an expense is incurred, not necessarily when the bill is settled. Cash accounting records actual bank movements.
Three common gaps:
Debtor timing. You invoice £50,000 in March, your customer pays in May. March looks profitable on the P&L. March feels empty in the bank.
Stock. You spend £30,000 buying materials in January for jobs that complete in April. That cash is gone in January; the revenue and profit land in April.
Corporation Tax and VAT. These appear as liabilities on your balance sheet but the actual payment might be months away. Easy to forget they're sitting there until the bill arrives.
The Three Numbers to Track Every Month
You don't need a 12-tab cashflow model to get on top of this. You need three numbers:
1. Cash runway
How many months can the business survive at current burn if no new revenue comes in?
Cash at bank ÷ average monthly outgoings = months of runway.
Below 2 months: red. 2–4 months: amber. Above 4 months: comfortable.
2. Debtor days
(Trade debtors ÷ annual revenue) × 365.
This tells you how long, on average, customers take to pay. UK SME average is around 38 days, but many businesses run at 60–90 without realising. Every 10 days of debtor time on a £500k revenue business is roughly £13,700 tied up in unpaid invoices.
3. Creditor days
(Trade creditors ÷ annual cost of sales) × 365.
How long you're taking to pay suppliers. Extending creditor terms is legitimate working capital management — as long as it doesn't damage supplier relationships or trigger late payment penalties.
The working capital cycle is debtor days minus creditor days. The wider that gap, the more cash the business needs to fund its own operations.
Five Practical Levers
Invoice immediately. The most common cash flow fix. Most businesses invoice at month-end or when they get around to it. Invoice on the day work is delivered or goods are dispatched.
Shorten payment terms. If you're on 60-day standard terms, try 30. Many customers will default to whatever you put on the invoice without questioning it.
Ask for deposits. For project work, a 30–50% upfront deposit is standard in most sectors. It's not aggressive — it's professional. It also weeds out clients who were always going to be difficult payers.
Use VAT as a planning tool, not a surprise. If you're on quarterly VAT returns, your liability builds up invisibly over three months and then hits all at once. Set aside the VAT portion of every sales receipt in a separate account (or at minimum a mental ringfence). Same logic applies to Corporation Tax — know your estimated bill each quarter, not just when the payment deadline arrives.
Negotiate supplier terms actively. Many suppliers default to 30 days but will extend to 60 if you ask and you're a reliable customer. That month can meaningfully smooth your cash cycle.
When to Get Ahead of It
Cash flow problems are much easier to solve six months out than six weeks out. A bank overdraft facility or invoice financing line is straightforward to arrange when the business looks healthy; it's nearly impossible when the business looks desperate.
If your debtor days are rising, your runway is shrinking, or you're regularly bridging the gap to payroll with your personal current account — those are the signals to act, not to wait and see.