You've just completed a £4,000 job. The customer promised to pay next week. But you need to buy materials for the next job on Monday. You've got £800 in the bank. You can't wait for next week.
So you charge it to your credit card. Interest starts accruing. By the time the customer pays and the balance clears, you've lost £150 to interest charges on a job you already completed.
This is the cash flow trap. You're doing profitable work. But money is moving at different speeds. You're paying suppliers upfront. Customers are paying you later. And the gap in between is killing your profit.
Most tradespeople treat cash flow as something that just happens. They don't track it. They don't forecast it. They just hope they have enough money when they need it. And half the time, they don't.
The ones who survive and grow are the ones with a system. Not a complicated accounting system. Just a simple cash flow system that tells them: where's the money coming in? When? Where's it going? When? And do I have enough between now and then?
The Three Sources of Cash Drain
Supplier Payment Timing: You buy materials on Monday. You pay the supplier on Friday. You use those materials on Wednesday. The customer pays you the following Monday. So between Friday and Monday, you've paid for materials you haven't been paid for yet. That's the gap.
Customer Payment Delay: You invoice the customer on Friday. They say they'll pay within 7 days. Sometimes they do. Sometimes they wait 14 days. Sometimes they wait 30 days. Every day they don't pay is a day your money is sitting in their bank account instead of yours.
Labour and Wages: If you have staff, you pay them weekly or monthly. But you bill customers on completion. So you're paying people before you get paid by the customer. The bigger your team, the bigger the gap.
Understanding these three gaps is the first step to managing cash flow.
The Cash Flow Forecast: Your Most Useful Tool
You need to know, for the next 30 days, when money is coming in and when it's going out.
This doesn't require fancy software. A spreadsheet works. Three columns: Date, Money In, Money Out. That's it.
Column one: Date — list every day for the next 30 days.
Column two: Money In — put in the date you expect customer payments. Not the date they say they'll pay. The date they usually actually pay. If a customer says they pay in 7 days but actually takes 10 days, put day 10. This is your actual cash forecast, not your hopeful one.
Column three: Money Out — put in every supplier payment you've committed to, every wage you need to pay, every fixed cost due. Be conservative. Include everything.
Now add them up by day. Running total. By day 5, you might be negative £800 (you've spent more than you've received). By day 12, you might be positive £2,000 (you've received customer payments and you're back in the black). By day 25, you might be negative again (another supplier payment due).
This forecast shows you your cash position for the entire month. More importantly, it shows you when you're going to be in a tight spot.
Example: Your forecast shows you'll be £1,200 in the red on July 18th. You know this today (July 1st). You can act now. You can ask customers to pay faster. You can delay a non-urgent supplier payment. You can arrange a business overdraft. But you can't act if you don't see it coming.
How to Collect Money Faster
Deposit on booking: Don't start work until the customer has given you a deposit. 50% of the job is standard. This covers your initial materials and secures their commitment. They're less likely to cancel if they've paid you upfront.
Progress payments on longer jobs: If a job will take more than three days, ask for a progress payment halfway through. "Once we're 50% through, I'll invoice you for half the remaining balance. That helps me cover materials for the second half." Most customers expect this and respect it.
Payment on completion: For smaller jobs, ask for payment when the work is done. Not "payment in 7 days." Payment now. You're in their home. Everything is complete. They should pay now. Many will. If they say they'll pay next week, that's a red flag.
Clear payment terms on the quote: Write on every quote: "Payment due on completion" or "50% deposit required to secure booking, balance on completion." Make it automatic, not something you have to ask for.
Follow up on overdue invoices immediately: If an invoice is due Friday and it's Monday and you haven't received it, message them same day. "Hi [name], just checking — did you receive the invoice? I want to make sure there were no issues." Friendly but proactive.
Most late payments aren't because the customer forgot. They forgot, or they're dealing with their own cash flow issues, or they think they have more time. A polite reminder works 80% of the time.
How to Manage Supplier Payments
You can't avoid paying suppliers. But you can manage the timing.
Negotiate payment terms: When you get a new supplier, don't just accept immediate payment. Ask: "What payment terms do you offer?" Many suppliers offer 30-day terms. You get materials today, you pay in 30 days. This is a huge help with cash flow.
Buy materials only when you're sure the job is booked: Don't buy materials speculatively. Wait until the customer has paid their deposit. Then buy. This means you're not paying for materials to sit in a van while you wait for the customer to decide.
Use suppliers strategically: Some suppliers require payment upfront. Some allow payment on 30-day terms. Work with the ones that allow terms. Yes, you might get slightly less discount, but the cash flow benefit is worth it.
Keep a minimum inventory: Don't stock materials "in case." Buy materials as you need them. The less cash tied up in inventory, the more you have available for operations.
The Emergency Fund That Saves You
Even with perfect forecasting, emergencies happen. A customer pays late. A job goes wrong and you need to buy replacement materials. A staff member needs emergency leave.
You need a cash buffer. Not an emergency fund for personal use. A business emergency fund.
How much? At minimum, enough to cover two weeks of fixed costs (wages, vehicle costs, insurance, rent). For most tradespeople, that's £2,000 to £5,000.
How do you build it? Every month, move 10% of profit into a separate account. Don't touch it unless it's an actual emergency. In six months, you've got a significant buffer.
Once you have this buffer, late customer payments stop being stress. A customer pays two weeks late? It doesn't matter. You have money in the bank. You pay suppliers and staff normally. The customer payment eventually comes and tops the buffer back up.
The difference this makes: Without a buffer, a late payment creates stress, forces you to make bad decisions, and costs you money in overdraft fees or credit card interest. With a buffer, it's just a minor inconvenience. Same business, completely different experience.
The Monthly Review That Prevents Disasters
Every month, sit down for 15 minutes and review:
1. How accurate was last month's forecast? You predicted you'd be short £500 on the 15th. Were you? Or was it £300? Or £1,000? Understanding your forecast accuracy helps you improve it.
2. What caused the biggest gaps? Was it a customer paying late? A supplier payment being earlier than expected? A job being delayed? Understanding the patterns helps you predict them.
3. Create next month's forecast. Same three-column spreadsheet. Money in, money out, running total. This is your management tool for the next 30 days.
4. Do I have enough buffer? If you hit a negative balance in next month's forecast, do you have enough cash to cover it? If not, what can you change? Can you ask a customer to pay faster? Can you delay a supplier payment? Can you take on an extra job?
This 15-minute review prevents surprises. You're not reacting to cash flow problems. You're managing them proactively.
Common Cash Flow Mistakes
Mistake one: Confusing profit with cash. You made £3,000 profit last month but you're overdrawn. This happens when customers haven't paid yet. Profit is real eventually. Cash is real right now.
Mistake two: Not forecasting beyond two weeks. You look at what's immediately due and don't see problems coming. Forecast 30 days out. Always.
Mistake three: Starting jobs without deposit. You commit time and materials without secured money. If the customer cancels or delays, you're stuck.
Mistake four: Accepting all customer payment terms. A customer says "30 days," and you agree. But 30 days from when? From the invoice date? From completion? From when they receive it? Ambiguity kills you. Be specific: "Payment due 7 days from invoice date."
Mistake five: Not tracking what customers actually pay in versus what they promised. You say "We get paid in 7 days on average." But do you? Or do you get paid in 10 days on average? Track the real data. Make forecasts based on that.
The System in Action
You finish a £2,000 job on Wednesday. You invoice immediately. You ask for payment on completion. Customer says they'll pay Friday. You know from experience they typically pay Monday, not Friday.
You update your cash flow forecast. You assume payment Monday.
You need to buy materials for the next job on Thursday. £600. You can cover it from your buffer or from previous customer payments already received. You don't go into overdraft.
The customer pays on Monday as predicted. Your buffer gets topped back up. You move on to the next job.
This is what good cash flow management looks like. No stress. No overdraft fees. No credit card interest. Just clear visibility of where the money is and when it's moving.
Start This Week
This isn't complicated. Open a spreadsheet. Write down every customer payment you're expecting in the next 30 days. Write down every supplier and wage payment due. Add them up.
Do you go negative at any point? That's your problem area. Now you can fix it.
Do this every month. In six months, you'll have eliminated most cash flow surprises. In a year, you'll have a buffer and a forecast system that works. Your business will run smoother because you'll stop being caught off guard.