The Cash-Flow Gap Between Purchase and Payment

Measuring the cash-flow gap accurately

Start with facts, not feeling. Pull the last five material-heavy jobs and write down two dates for each: the date the merchant invoice actually cleared your bank and the date the customer’s payment actually cleared. Don’t use ‘date paid’ from an invoice PDF or the day a client said they’d pay — use the cleared funds date on your bank statement. Include any supplier part-payment dates and card merchant hold times. This gives you the raw gap for each job: merchant-outflow date to customer-inflow date. You’ll be surprised how often that gap is longer than the one you thought you had.

Once you have those raw numbers, calculate the gap in days for each job and then find the average. Look for patterns: does the gap blow out on large jobs, when you used a credit card, or when a supplier uses end-of-month settlement? Note the outliers and why they happened. If a supplier’s trade account requires invoices to be paid 30 days end of month, that changes your arithmetic. Record these settlement rules beside each job so you can see exactly where the timing mismatch comes from.

Finally, convert that average into cash terms. Work out the total material cost per job and multiply by the average gap in days to see how many ‘cash-days’ you’re funding. That figure tells you how much working capital you tie up between buying materials and getting paid. Use it to stress-test the business: could you cover two or three such gaps at once? If not, that’s your signal to change payment terms, use deposits, negotiate supplier terms or bring in short-term finance. Knowing the number focuses your actions.

Deploying deposits smartly

A deposit changes the game. It gives you cash before you buy and reduces the days you’re out of pocket. Aim to cover at least the cost of materials with the deposit, not just a token amount. For a kitchen refit that needs £5,000 of cabinets, a realistic deposit might be 40–50% to cover the order. For a small repair job a third may suffice. Call it what it is: a commitment payment to secure materials and booking. Saying ‘deposit’ frankly keeps the relationship professional and weeds out tyre-kickers who slow you down.

Be clear about the deposit terms in writing. State whether it’s refundable, when it’s deducted from the final invoice, and what happens if the client cancels. Simple contracts and an upfront email confirming the deposit details stop arguments later. If you take card payments for deposits be mindful of merchant fees and refund rules. For larger jobs consider staged deposits: an initial booking deposit, a materials release payment, and another on delivery. That spreads the risk and keeps cash coming as the job progresses.

When clients balk, explain the reality: you buy materials before they pay and those goods must be paid for to guarantee delivery. Use real examples from the job — ‘I’ll need £1,800 to order the roof battens and tiles; without that I can’t book the scaffold’. Most householders understand this practical angle. If a client refuses any deposit, treat it as a red flag. Either charge a premium for starting without one or walk away. Running a business without deposits is like running a van with no spare wheel — risky and avoidable.

Using staged payments to optimise cash-flow

Staged payments keep cash moving and reduce your exposure. For jobs lasting longer than a week, break the total into logical milestones: site set-up, materials on-site, mid-way completion, then completion. A common split might be 30% deposit, 40% on delivery/halfway, 30% on completion. Link each invoice to a clear, measurable milestone: delivery note, scaffold up, first fix complete. Don’t make the stages vague or subjective; clients accept payment stages when they can see the work that triggered each invoice.

Communicate the staged plan before you start and repeat it at handover. Put the schedule on the quotation and re-state it in your first email after acceptance. Use photos and short progress notes with each invoice so customers see what they’re paying for. For VAT-registered businesses, remember VAT is due on the invoice date, not payment; include clear VAT breakdowns so clients aren’t surprised. If a client delays a staged payment, stop work until payment is cleared — set that expectation upfront and stick to it.

Staged payments also protect you from scope creep. If the client asks for extras, quote them as variations with their own payment stage. That keeps the original job funded and prevents you subsidising extras. For long programs, include a monthly or fortnightly interim valuation for works done, especially on site projects like extensions or conversions. Interim invoices maintain steady cash-flow and are easier for clients to accept than a huge final bill they have to find in one go.

Leveraging trade accounts and supplier terms

Supplier credit is free working capital if you manage it. Many builders merchants offer 30 days end of month or 14 days terms — use those to push your merchant-outflow date back towards your customer-inflow date. Don’t confuse supplier terms with free money: they’re credit that needs managing. Keep a list of each supplier’s settlement date and plan purchases so large orders land after your client payments. For multiple suppliers, stagger orders to avoid lumping several 30-day payments into the same week.

Negotiate better terms as you grow. Ask suppliers for longer terms on big orders or for temporary increases during peak months. A reliable payment history and regular orders give you leverage. Offer to become a regular customer in exchange for 45-day terms, or negotiate part-payment for special items. Be realistic: new traders may get shorter terms, but demonstrating prompt payments builds trust and opens doors to larger credit lines. Trade accounts are a tool — use them intentionally, not randomly.

Watch the downside: late supplier payments can cost you in cash-flow and relationship damage. Don’t use supplier credit to cover poor margins; the goal is to match supplier outflows to client inflows. If early-pay discounts are offered, calculate whether the percentage saved is worth tightening your cash position. Sometimes a small discount is worthwhile, other times you need the float more. Keep a supplier diary in your accounts system so you always know when big bills are due and can plan accordingly.

Practical routines and tools to keep the gap closed

Routine beats panic. Set up a simple weekly cash-flow check: list incoming expected client payments, scheduled supplier settlements, and any planned material purchases. Use a spreadsheet or basic accounting software — it doesn’t need to be fancy. The point is to see the next 30 days at a glance. Colour-code urgent outflows and incoming payments. If a supplier invoice and a client payment fall in the same week, you either shift the order, defer the supplier payment using your account, or chase the client for a staged payment. Weekly checks prevent surprises.

Keep job-level ledgers. For every job have a one-page record: material costs, labour, deposits taken, staged invoices sent and cleared, and remaining balance. Update it the day you pay a supplier and the day you clear a client payment. That lets you calculate your true working capital tied to each project. If you run two or three jobs at once and your ledger shows you’re funding £8,000 of materials without cover, you’ve got to act — either take deposits on new jobs, slow new starts, or use short-term finance.

Use technology sensibly. Accounting packages that link bank feeds and let you send online invoices cut the admin and help with chasing. Set automatic payment reminders and enable online payments to make it easier for clients to pay straight away. Equally, don’t ignore the old-fashioned phone call. A calm, professional call to a client who owes money often speeds things up more than automated emails. Train your communication: polite but firm. The trades that get paid on time combine tech with consistent, human follow-up.

Handling problem customers and jobs

Not every job will pay on time. Plan for the worst and you’ll be less likely to get hammered. If a client misses a staged payment, stop work and issue a written notice that work will pause if payment isn’t made by X date. Document everything: photos, emails, texts and delivery notes. That paper trail matters if you need to escalate. Use retention clauses for larger projects and keep a holdback for snagging — it gives you leverage and ensures you’re not left chasing after completion to get paid.

If a client refuses to pay, use the formal routes calmly: mediation, small claims court or adjudication depending on job size and contract terms. Don’t escalate straight away to threats; try negotiation with a payment plan first. For household clients, the small claims track is straightforward but takes time; for commercial clients, tightening up contract terms and including interest on late payments often pressures them to settle. Always be factual: supply dates, invoices, and proof of work. That keeps you credible and avoids wasting time on clients who won’t pay.

When a job goes bad, learn and adapt. Did you get lumbered because you started without a deposit? Were materials ordered for a client who then delayed? Change your checklist to prevent repeat mistakes. Consider requiring larger deposits from clients with poor references or from those who give you a smell test. For repeat commercial clients, set account limits. Protect the business first: sometimes walking away early from a potential headache is the best call. You want clients who pay on time, not those who erode your margins and morale.

Common mistakes

• –Never actually measuring the gap, so problems only show up as a vague sense of being skint.
• –Relying on trade credit alone without a deposit, so the gap just moves rather than closes.
• –Assuming the gap is the same on every job type when material-heavy jobs behave very differently to labour-heavy ones.
• –Using overdraft as a permanent fix for a gap that a better deposit structure would close.

Questions people ask

What's a healthy cash-flow gap for materials?

Zero or negative — meaning customer money arrives at or before the time you have to pay the merchant. A positive gap of more than a few days on material-heavy jobs usually needs fixing.

Does a cash flow forecast help with this?

Yes — a simple week-by-week forecast that includes known merchant payment dates and expected customer payments makes the gap visible before it becomes a problem.