Managing Cashflow in Construction

Zubair Aslam
Jul 30
7 min read

Key Takeaways

Cash flow is the biggest reason profitable construction businesses fail — you can be busy and profitable on paper yet run out of cash.
The Construction Act gives you real tools to get paid: if a payer doesn't issue a valid "pay less notice" in time, they owe you the full sum you applied for, and you have the right to suspend work and go to adjudication.
On overdue commercial invoices you can charge statutory interest of 8% above the Bank of England base rate, plus fixed compensation of £40, £70 or £100 per invoice.
Retentions (typically 3–5%) tie up your cash for months or years — track them and chase their release actively.
Staying solvent comes down to forecasting, holding a cash buffer, and setting money aside for tax, VAT, and CIS as you earn it. A specialist construction accountant like SiteLedger notify you proactively with tax bill warnings.

Cash flow is the single biggest reason profitable construction businesses go under. You can be winning work, staying busy, and turning a profit on paper, yet still run out of money — because in construction the cash comes in slowly and unevenly while your costs go out fast. Getting paid on time and keeping enough cash in the bank are two different skills, and a healthy construction business needs both. Here's how to manage each.

Why cash flow is harder in construction than anywhere else

In most industries, businesses invoice, get paid, and move on. Construction stacks the odds against you in ways few other sectors face:

You pay out before you're paid. Materials and labour come out of your pocket first; the money for the work arrives weeks or months later.
Retentions. A slice of every payment is held back, sometimes for a year or more after the work is done.
Long payment chains. Client to main contractor to subcontractor to sub-subcontractor — a delay anywhere upstream cascades down to you.
CIS deductions. For subcontractors, 20% is taken from your labour at source and tied up with HMRC until you file.
The VAT reverse charge. VAT-registered subcontractors no longer collect VAT from contractors, losing a cash buffer they used to hold on to between VAT returns.

None of these are things you did wrong — they're built into how the industry pays. Managing them is the job.

Getting paid: know your rights under the Construction Act

The Housing Grants, Construction and Regeneration Act 1996 — the "Construction Act" — gives you statutory payment rights on most construction contracts, regardless of what the contract itself says. These are worth knowing, because most subbies never use them:

The right to interim or stage payments on any contract expected to last more than 45 days, so you're not waiting until the end of a long job to see any money.
Payment notices and the "pay less notice." After you apply for payment, the payer must tell you what they intend to pay. If they want to pay less than the sum you applied for, they must serve a valid pay less notice before the final date for payment. If they miss that deadline, they owe you the full amount you applied for — this is the basis of what's known as a "smash-and-grab" adjudication, and it's one of the most powerful levers you have.
The right to suspend work for non-payment. If you're not paid in full by the final date and no pay less notice was served, you can suspend some or all of your work after giving seven days' notice — and claim the costs of stopping and restarting.
The right to adjudication at any time. Adjudication is a fast dispute-resolution process — a decision within 28 days — that's far cheaper and quicker than court, designed specifically to keep cash moving in construction.
"Pay-when-paid" clauses are banned. A contractor generally can't refuse to pay you just because they haven't been paid further up the chain (the exception is genuine insolvency). The same goes for "pay-when-certified" terms.

Knowing these rights changes the conversation with a slow payer. This is an area where a construction-specialist accountant or advisor is worth having in your corner, because used correctly the pay less notice rule alone can unlock money you're owed.

Getting paid: the practical habits

The law helps, but good process prevents most problems in the first place:

Agree clear written payment terms up front — amounts, dates, and how and when you apply for payment.
Submit your applications and invoices promptly and correctly. A late or ambiguous application can cost you an entire payment cycle, so get the timing and detail right.
Invoice the moment a milestone is hit — don't sit on invoices; every day you delay is a day added to when you're paid.
Chase early and systematically — a polite reminder before the due date, a firm follow-up straight after. The businesses that get paid fastest are the ones that ask.

Late payment: your statutory rights

When a business customer pays late, you're legally entitled to charge statutory interest of 8 percentage points above the Bank of England base rate (11.75% in mid-2026, as it moves with the base rate), plus a fixed compensation sum — £40 for debts under £1,000, £70 for £1,000 to £9,999.99, and £100 for £10,000 or more. This applies automatically to commercial debts, even if your contract says nothing about interest, and it isn't subject to VAT. You don't always have to enforce it, but raising it — or adding it to a statement — is often enough to move a stubborn payer.

Retentions: the slow drain on your cash

Retentions are a normal part of construction, but they're a genuine cash-flow drag. Typically 3–5% of each payment is withheld, with half released at practical completion and the rest after the defects liability period, often 6 to 12 months later. That's your money, earned, sitting in someone else's account. Track every retention, diarise the release dates, and chase them actively — unclaimed retentions are one of the most common ways construction businesses quietly lose money. The Construction Act also means the release of your retention can't be made conditional on some other contract being settled.

Staying solvent: manage the cash, not just the profit

Profit and cash are not the same thing, and construction businesses fail on the second even when the first looks fine. The habits that keep you solvent:

Forecast. Keep a rolling short-term cash-flow forecast — 13 weeks is a good horizon — so you can see a squeeze coming while there's still time to act.
Hold a buffer. Keep a cash reserve big enough to cover the gap between paying out for a job and getting paid for it. In construction that gap can be months.
Set aside tax as you earn. Move money for Income Tax or Corporation Tax, VAT, and payments on account into a separate account as it comes in, so it's never spent by accident. Your construction accountant will help you with this.
Speed up your VAT refunds. If the reverse charge has turned you into a repayment trader — reclaiming VAT on materials but charging none on your sales — switching to monthly VAT returns gets those refunds back four times faster than quarterly.
Watch margins job by job. One loss-making contract can drain the cash from three profitable ones. Know where you're actually making money. SiteLedger Construction Accountants provide free software that will do this automatically, in real-time.

Warning signs to act on

Cash-flow trouble is far easier to fix early. Treat these as signals to act now, not later:

You're relying on the next payment to cover the last job's costs.
You've dipped into VAT or CIS money you'd set aside to fund day-to-day spending.
You keep working for a client who always pays late.
You genuinely don't know how much you're owed or when it's due.

If any of these ring true, deal with it before it becomes an insolvency problem — the earlier you act, the more options you have.

Frequently Asked Questions

Why do construction businesses struggle with cash flow? Because they pay for materials and labour before they get paid for the work, and the money comes in slowly and unevenly — held back by retentions, long payment chains, CIS deductions at source, and the VAT reverse charge. A construction business can be profitable and busy yet still run short of cash, which is why cash flow, not profit, is the most common cause of failure in the sector.

Can I charge interest on late payments? Yes. On overdue commercial invoices you can charge statutory interest of 8% above the Bank of England base rate, plus fixed compensation of £40, £70, or £100 depending on the size of the debt. This applies automatically under the Late Payment of Commercial Debts (Interest) Act 1998, even if your contract doesn't mention interest, and it isn't subject to VAT.

What is a pay less notice? It's the notice a paying party must serve if they intend to pay you less than the sum you applied for, before the final date for payment. If they don't serve a valid pay less notice in time, they're generally required to pay the full amount you applied for — which is why the rule is such a powerful tool for getting paid. If that happens, you can pursue the sum through a quick "smash-and-grab" adjudication.

Can I stop work if I'm not being paid? Yes. Under the Construction Act, if you're not paid in full by the final date for payment and no pay less notice was served, you have the right to suspend some or all of your work after giving seven days' notice, and to claim the reasonable costs of suspending and restarting. It's a formal right, so it's worth taking advice before using it to make sure you follow the process correctly.

How much cash should a construction business keep in reserve? Enough to cover the gap between paying out for work and getting paid for it, which in construction can run to several months. The right figure depends on your payment terms, retentions, and how long your typical jobs take, so the practical answer is to build a cash-flow forecast and hold a buffer sized to the worst gap it reveals.

Struggling to stay on top of cash flow?

Getting paid on time and keeping enough in the bank is where a lot of good construction businesses come unstuck — and it's rarely about profit. Talk to the SiteLedger team on 0161 513 0027 and we'll help you forecast your cash flow, tighten up how you get paid, and plan around CIS, VAT, and retentions. As construction-specialist accountants, keeping building businesses solvent is exactly what we do.

Written by the SiteLedger team — construction-specialist accountants. Last reviewed: July 2026. Figures reflect the position in the 2026/27 UK tax year; the statutory interest rate moves with the Bank of England base rate. This is general guidance, not personal financial or legal advice; speak to us about your situation, and take legal advice on contentious payment disputes.