Retention Disputes in Construction: A Complete Guide

Retention is a slice of money — usually 3% to 5% of each payment — that an employer or main contractor holds back from a builder or subcontractor as security that the work will be completed and any defects put right. Typically half is released at practical completion and the other half once the defects (or rectification) period ends and the certificate of making good is issued. Disputes erupt when that money is never released, when the payer becomes insolvent, or when “defects” are used as an excuse to keep cash indefinitely.

For subcontractors, retention is a serious cash-flow problem: it is your profit margin, frozen for months or years, while you have already paid for labour and materials. For employers and main contractors, it is a familiar lever to ensure snags get fixed. The tension between those positions is why retention generates so much friction — and why it is now squarely in the sights of UK reform.

This guide explains what retention is, how it appears in JCT and NEC contracts, its legal status, the most common dispute triggers, how the Construction Act payment rules apply to release, how to recover retention through adjudication, and the genuinely significant 2026 reform position — a proposed outright ban — together with practical steps to protect your money.

What retention money is

Retention (sometimes called “retainage”) is a contractual mechanism by which the paying party deducts and holds back a small percentage of each interim payment otherwise due to the party carrying out the work. It is not a penalty or a fee — it is security held against two things: that the works will reach completion, and that any defects appearing afterwards will be put right.

The standard structure has three stages. During the works, a fixed percentage — commonly 3%, sometimes 5% — is deducted from each valuation. At practical completion (the point at which the works are complete enough to be used, bar minor snags), the retention percentage is typically halved: the first tranche is released. The remaining half is held through the defects liability period (also called the rectification or defects correction period — often 6 to 12 months), and released only once the contract administrator issues the certificate of making good, confirming that any notified defects have been remedied.

So on a contract with a 5% retention, you would normally see 2.5% released at practical completion and the final 2.5% released months later. The exact figures are whatever the contract says — there is no statutory rate.

Why retention exists — and the cash-flow problem

From the employer’s and main contractor’s perspective, retention is a behavioural tool. Holding a meaningful sum until defects are fixed gives the contractor a financial incentive to return to site and snag the work rather than walking away once paid. It also provides a ready pot of money the employer can, in principle, draw on if the contractor fails to remedy defects.

The problem is what retention does to the party further down the chain. Retention is held against money the subcontractor has already earned. The subcontractor has typically already paid wages, hired plant and bought materials — yet 3%–5% of every invoice is frozen, often for a year or more after their work is finished. Because margins in construction are thin (frequently 2%–4%), the retained sum can exceed the entire profit on a job. Industry estimates have repeatedly put the total value of retentions held across the UK construction supply chain in the billions of pounds, much of it owed to small and medium-sized firms least able to absorb the cash-flow hit.

This is the structural unfairness at the heart of the debate: the money belongs to the firm that earned it, but it is held by someone else, who has every incentive to release it slowly — or, in the worst cases, not at all.

Retention in JCT and NEC (X16) contracts

The two dominant UK standard-form families handle retention very differently.

JCT contracts

Most JCT contracts build retention directly into the payment mechanism. The contract sets a “Retention Percentage” — the default is often 3% on larger forms, though parties frequently amend it (5% is common). The JCT mechanism distinguishes between a higher percentage applied to work that has not reached practical completion and a reduced percentage (usually half) once it has. Importantly, JCT forms also state that the employer’s interest in the retention is fiduciary as trustee — meaning the retention should be held on trust for the contractor — and allow the contractor to require the sum to be placed in a separate bank account. Most JCT forms also enable a retention bond as an alternative to cash, with JCT publishing template bond wording.

NEC contracts

Under NEC contracts (such as the Engineering and Construction Contract), retention is not applied unless the parties choose it. It must be expressly incorporated through secondary Option X16. Where X16 is used, the parties state a retention percentage and a “retention free amount” (a threshold below which nothing is retained). Retention is reduced as the Price for Work Done to Date rises above that threshold, and the withheld money is released on the issue of the Defects Certificate, which marks the end of the defects correction period. NEC’s drafting is deliberately clearer and more administrative than JCT’s, but it does not, on its own, create a trust.

The legal status of retention and trust funds

Legally, retention money is the contractor’s money that the employer is permitted to hold back temporarily. It is not the employer’s to spend. Several standard forms — JCT among them — go further and say the retention is held on trust for the contractor. The significance of a trust is what happens on insolvency: money held on a valid, properly constituted trust does not form part of the insolvent party’s general assets and is therefore protected from ordinary creditors.

The catch is well known to the courts and the industry: a trust over retention is only effective if it is actually set up. English law generally requires that, for retention to be impressed with a trust, the money is identifiable and — critically — set aside in a separate, designated account before insolvency strikes. In practice, contractors rarely insist on this, and employers rarely volunteer to do it. The retention typically sits mixed in with the payer’s general working capital. So when the payer goes under, the “trust” is illusory: there is no segregated fund to claim, and the subcontractor ranks as an unsecured creditor, usually recovering pennies in the pound or nothing at all. This gap — a trust on paper that almost never exists in fact — is one of the strongest arguments for reform.

Common dispute triggers

Retention disputes tend to cluster around a handful of recurring causes.

• Insolvency up the chain. The most damaging trigger. If the main contractor or employer becomes insolvent while holding retention, the subcontractor’s money is usually lost because no trust fund was set up.
• Failure to certify. Release of retention is often tied to a certificate (practical completion, making good). If the contract administrator simply does not issue the certificate, the money is never triggered — even though the milestone has been reached in fact.
• Disputed defects. The payer alleges defects to justify keeping the second tranche. Sometimes genuine; sometimes a pretext. The size of the defect rarely bears any relation to the retention withheld.
• Never-ending defects liability. Some payers treat the rectification period as open-ended, or raise fresh snags to reset the clock, so the final release date never arrives.
• Set-off and abatement. The payer claims a right to deduct other sums (delay damages, back-charges) from the retention.
• Missing pay-less notices. Where retention is withheld at final account stage without a valid pay-less notice, the deduction may simply be unlawful under the Construction Act — turning a “defects” argument into a clear-cut payment claim (see final account disputes).

Many of these overlap with broader construction payment disputes, and the same statutory weapons apply.

The Construction Act payment framework

Retention is part of “the sum due” under a construction contract, so the payment-notice regime in the Housing Grants, Construction and Regeneration Act 1996 (as amended by the 2009 Act) governs how and when it can be withheld. The framework, in outline, runs:

1. A due date for each payment, fixed by the contract (or by the statutory Scheme if the contract is silent).
2. A payment notice — typically within five days of the due date — stating the sum considered due and the basis for it.
3. A pay-less notice if the payer intends to pay less than the notified sum. It must state the amount the payer considers due and how it is calculated, and be given before the prescribed deadline (under the Scheme, no later than seven days before the final date for payment).
4. A final date for payment, by which the sum must actually be paid.

The practical consequence is decisive. If retention is withheld at final account or release stage but the payer has not served a valid pay-less notice in time, the payer is generally obliged to pay the full notified sum regardless of any defects argument. The defects dispute does not disappear, but it cannot be used to justify holding money now if the notice machinery was not followed. You can see the detail of the official regime on legislation.gov.uk and in the Government’s guidance on commercial payment.

Recovering retention via adjudication

The Construction Act gives every party to a construction contract the right to refer a dispute to adjudication “at any time”. This is the workhorse remedy for retention disputes, and for good reason:

• Speed. An adjudicator typically reaches a decision within 28 days of referral (extendable by agreement), versus many months or years in court.
• Cost. Far cheaper than litigation, and you bear your own costs but can recover the principal sum.
• Enforceability. The decision is temporarily binding — the parties must comply, and the courts enforce adjudication decisions robustly, even if the dispute is later litigated.

For retention, two routes are common. The first is a “smash-and-grab” claim: if the payer failed to serve a valid payment or pay-less notice, you adjudicate for the full notified sum on the notice failure alone, without arguing the merits of any defect. The second is a “true value” claim: you ask the adjudicator to value the work (and any defects) and decide what is actually due — useful where notices were served but you say the defects deductions are overstated. Our guide to construction adjudication walks through how to prepare and run a referral.

The reform debate and 2026 ban proposal

Retention reform has been debated for years. The voluntary industry route ran through Build UK, which in 2018 published a “Roadmap to Zero Retentions” with the ambition of eliminating retentions by the end of 2025, alongside Minimum Standards giving drafting guidance for JCT and NEC. The voluntary approach made some progress on transparency but did not achieve industry-wide abolition, and the 2025 target was effectively dropped. Earlier private members’ bills — including Construction (Retentions Abolition) Bills aimed at ring-fencing or banning cash retentions — were introduced in Parliament over several sessions but did not become law.

The position changed materially in 2025–26. Between 31 July and 23 October 2025 the Department for Business and Trade ran a major consultation on late payment, with retention as a central issue, offering two options: a statutory protection (ring-fencing) scheme, or an outright prohibition. On 24 March 2026 the Government published its response, Time to Pay Up, announcing it intends to take forward the more radical option: to prohibit the deduction and withholding of retention payments under construction contracts. The Government described the wider package as the most significant action on late payment in over 25 years, alongside a proposed 60-day hard cap on payment terms and statutory interest on late payments.

Current 2026 status — read carefully. This is a stated policy intention, not yet law. The Government expressly said that, “given the ambition of the policy”, it will consult further on the impact before taking a final decision on implementation, and the relevant legislation (announced as part of the wider late-payments package) has been introduced to Parliament but has not completed its passage. So as at June 2026, cash retentions remain lawful and enforceable; the direction of travel is plainly towards abolition, but anyone relying on the change should treat it as forthcoming, not in force. You can follow the official position via the Government’s Time to Pay Up announcement and the consultation outcome on GOV.UK.

Practical steps to protect your retention

Until any ban takes effect, retention is a risk you manage contractually and administratively.

• Negotiate it down or out. Push for a lower percentage, a lower retention-free threshold (NEC X16), or no retention at all — increasingly accepted on public-sector and well-run private contracts.
• Use a retention bond instead of cash. A bond substitutes an insurer’s promise to pay for cash held in someone else’s account, removing your insolvency exposure entirely.
• Insist on a trust account. Where the contract provides for it (JCT does), require the retention to be placed in a separate designated account and ask for evidence it has been done.
• Diarise the release dates. Track practical completion and the certificate of making good. The day a milestone is reached, write and request release in writing.
• Police the notices. If retention is withheld, check whether a valid pay-less notice was served on time. If not, adjudicate.
• Watch the payer’s solvency. Credit-check up the chain and act early on warning signs — once insolvency hits, unsecured retention is usually gone.
• Resolve defects formally. Don’t let “snags” drift; agree a written list and completion dates so the final tranche cannot be held hostage by an open-ended defects argument (see defective works claims).

Common mistakes to avoid

• Treating retention as gone money. It is your earned income; budget to chase and recover it, not to write it off.
• Missing the release trigger. Not diarising practical completion or the making-good certificate means the money never gets requested.
• Ignoring the notice regime. Arguing the merits of defects when the real point is that no valid pay-less notice was served — the quickest route to recovery.
• Accepting cash retention without protection. Taking cash retention from a financially shaky payer with no bond and no trust account is taking on their insolvency risk for free.
• Letting the defects period run open-ended. Failing to pin down a closed snag list lets the payer keep resetting the clock.
• Delaying adjudication. The right to adjudicate exists “at any time” — waiting only worsens your cash flow and risks the payer’s solvency deteriorating.

Frequently asked questions

This article is for general information only and does not constitute legal or accountancy advice. Hayhills Limited, trading as Hayhills Legal Advisory, provides non-reserved legal advisory services. Always check current requirements at GOV.UK.