Summary

Trade businesses make a profit on the job and lose money on the timing. A 6-week job at 30% gross margin generates £6,000 profit on a £20,000 contract — but if the customer takes 90 days to pay, the trader has financed £15,000 of materials and labour out of pocket for three months. Two or three of those concurrently and the bank account is empty.

The cash flow problem is more dangerous than the profit problem because it kills businesses faster. A 5% margin business with disciplined cash flow can survive recessions; a 25% margin business with chaotic cash flow goes bust on a single slow payer. UK trades have above-average insolvency rates not because they're bad at the trade, but because they're bad at the cash management.

The defences are well-known and not difficult to apply — deposits, staged payments, fast invoicing, late-payment chasing, working-capital reserve, tax-account discipline. What's hard is treating the cash discipline with the same priority as the trade work. This article covers the practical mechanics, the legal protections, the software stack that makes it manageable, and the warning signs of an impending cash crisis.

Key Facts

Quick Reference Table

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Cash Flow Lever Effect Typical Implementation
Take a deposit Immediate cash on commit 30–50% on jobs >£1,000
Stage payments Cash mid-project First fix / second fix / completion
Invoice immediately Reduces DSO by 5–10 days Invoice on day of completion, not end of month
7-day terms residential Reduces DSO by 14–21 days Default 7 days for domestic; negotiate from there
Pre-order material direct Customer pays supplier Avoid carrying material cost
Card payment on completion Same-day cash Stripe, Sumup, GoCardless
Direct debit for retainer Predictable cash Maintenance contracts, repeat customers
Factoring / invoice finance Cash within 24h of invoice Costs 1–3% of invoice value
Trade credit account Defers material payment 30 days Travis Perkins, City Plumbing, etc.
Reserve Account Target Balance Purpose
Operating working capital 6 weeks of overheads Survive payment delays
VAT account All VAT received Pay HMRC on quarter end
Tax (Self-Assessment) account 20% of net profit (or 40% higher rate) Pay 31 Jan + 31 July
CIS deductions account Withheld portion of subcontractor pay Pay HMRC monthly
Equipment reserve 10% of revenue annually Van replacement, tool upgrades
Software Tool Typical Cost (UK) Use Case
Xero £15–£59/month Accounting + invoicing
QuickBooks £12–£55/month Accounting + invoicing
FreeAgent £19–£35/month (free with NatWest business) Accounting + invoicing
Sage Business Cloud £14–£36/month Accounting + payroll
Sumup card reader £39 one-off + 1.69% transaction Card payments on site
Stripe 1.5% + 20p per UK card transaction Online card payments
GoCardless 1% + 20p per Direct Debit Recurring/scheduled payments
ServiceM8 / Jobber / Tradify £24–£89/month Job + invoicing + CRM (trade-specific)

Detailed Guidance

The Deposit Discipline

Deposits are the single most important cash flow tool. Take a deposit on every job over £1,000. Typical scales:

Customers expect to pay a deposit on substantial work; the trade convention has normalised it. Refusing to pay a deposit on a £15,000 extension job is a red flag for the customer's own cash position — the kind of customer who walks at completion without paying.

Document the deposit in the quote: "30% deposit on acceptance; balance on completion." This makes it part of the contract; refusing to pay the deposit is then a contract issue, not a "we'll sort it out later" problem.

Stage Payments

For jobs longer than 2 weeks, structure stage payments to match milestones:

Each stage payment is invoiced at the milestone and due within 7 days. This matches your cash outflows (paying for materials and labour week-to-week) against cash inflows.

Fast Invoicing

The fastest cash collection improvement is invoicing on the day of completion, not at the end of the month. A "month-end invoicing" habit adds 14–21 days to your average payment time on every job — translating directly to a working capital requirement.

Use invoicing software (Xero, QuickBooks, FreeAgent) on a phone — generate the invoice on site at the end of the job, email or text to the customer immediately. Many systems integrate with card payment so the customer can pay on the spot.

Late Payment Recovery

The Late Payment of Commercial Debts (Interest) Act 1998 gives B2B suppliers (sole traders included) the right to charge:

The statutory right exists regardless of contract terms. You don't need to mention it on the invoice (though it helps).

For chasing:

  1. Day 1 past due: friendly reminder email/text
  2. Day 7 past due: formal late payment notice citing the Act
  3. Day 14 past due: final demand, threat of court action
  4. Day 21 past due: file Money Claim Online (£35–£455 court fee depending on claim size)
  5. If unpaid after judgment: enforcement (warrant of control, etc.)

Most chasing succeeds at steps 1–3. The Money Claim Online stage is usually enough to prompt payment — businesses don't want CCJs on their record.

Domestic customers fall under different rules (Consumer Rights Act 2015) — the late payment Act applies to B2B only. For domestic, the recovery route is Small Claims Court (also via Money Claim Online), with interest on the judgment (currently 8% statutory) once entered.

CIS and Subcontractor Cash Flow

For contractors using subcontractors under CIS:

For subcontractors:

Reverse Charge VAT (Construction)

Since March 2021, the construction industry uses "domestic reverse charge" VAT for B2B services to other CIS contractors:

This matters for cash flow because:

Set up your invoicing software to handle reverse charge correctly; HMRC will fine for incorrect VAT treatment.

The VAT and Tax Reserve

A common cash flow disaster: trader sees a healthy bank balance, spends it, then quarter-end VAT bill arrives for £15,000 and the bank is empty.

The fix: open a separate "tax savings" bank account. Every invoice received that includes VAT, transfer 20% of the gross to the tax savings account immediately. Every payment received that includes net profit, transfer 20% (basic rate self-employed) or 40% (higher rate) of the profit portion to the tax savings account.

When the VAT or Self-Assessment bill arrives, the money is already there. The trick is to treat tax money as not-yours-to-spend, regardless of how the bank balance looks.

Working Capital Buffer

Hold a working-capital buffer of 6–8 weeks of operating costs (excluding owner drawings). This covers the typical worst case of a 4-week customer payment delay + 2-week material/labour outflow gap.

For a £200,000 turnover trade business with 15% net margin (£30,000 net), operating costs are ~£170,000 — so 6 weeks of operating costs is ~£20,000.

This sits in an instant-access savings account, separate from your operating account. Don't touch it for normal cash flow; use only when payment is delayed or a job goes wrong.

Warning Signs

Watch for:

  1. Increasing trade receivables — Customers taking longer to pay than usual
  2. Increasing trade payables — You stretching out paying suppliers
  3. Using the tax account for operating cash — Bad sign; HMRC will come knocking
  4. Refusing small jobs to take big ones with long payment — Cash flow concentration risk
  5. Personal credit card balance increasing — Funding the business through personal debt
  6. Repeatedly missing supplier discount windows — Cash too tight for 30-day pay

Any of these for more than a quarter is a cash flow problem. Address it with: better deposits, faster invoicing, late-payment chasing, scaling back work intake until balance restored.

Software Setup

A typical UK trade business setup in 2026:

The total monthly software cost is £30–£100. Compared to the cost of one bad-debt write-off (£500–£5,000+) this is excellent value.

Worked Example: Cash Position Through a £20,000 Extension

Job: 6-week single-storey rear extension, contracted at £20,000 + VAT (£24,000). Trade gross margin 25% (£5,000 net), VAT to remit £4,000.

Without cash discipline:

With cash discipline:

The same job at the same margin. Different cash position. Different ability to take the next job.

Frequently Asked Questions

How much deposit can I legally take?

For residential customers under Consumer Rights Act 2015, deposits are permitted as long as they're reasonable in relation to the expected costs the trader incurs before completion. 30% on a typical extension is unquestionably reasonable. 80% upfront on a job not yet started would not be.

For commercial customers, deposit terms are whatever the contract says — there's no statutory limit.

Can I charge late payment fees to a residential customer?

The Late Payment of Commercial Debts (Interest) Act 1998 does NOT apply to consumer (residential) customers. You can charge late payment fees only if specifically agreed in the contract — make it part of your written terms before signing.

For commercial (B2B) customers, the Act applies automatically — you can charge interest + fixed compensation without needing a contract clause.

What's the difference between Xero, QuickBooks, and FreeAgent?

All three do the same core job (accounting, invoicing, expense tracking, VAT, MTD compliance). Differences:

Pick one and commit; switching mid-year is painful.

How do I handle a customer who refuses to pay?

Don't escalate emotionally; follow process:

  1. Polite reminder (day 1 past due)
  2. Formal late payment notice citing Act 1998 (day 7)
  3. Final demand (day 14)
  4. Money Claim Online (day 21+)
  5. If granted, enforce via Warrant of Control or bailiff (£100+ court fee)

Most non-payers respond before step 4. Document everything: the quote, the contract acceptance, the work-completed evidence (photos), and the chasing correspondence. The court process is straightforward when your documentation is in order.

What's the maximum I should let trade credit (supplier debt) grow to?

A rule of thumb: trade payables shouldn't exceed your average monthly material cost. If you owe Travis Perkins £20,000 and your monthly trade purchases are £5,000, you're 4 months behind — they'll suspend your account before long.

Keep supplier accounts current as a discipline. Stretch them only in genuine emergency, not as a routine cash flow technique.

Regulations & Standards