Retention in Construction Contracts

Introduction

Retention is one of the most familiar — and most contested — mechanisms in UK construction contracts. A percentage of each interim payment is withheld by the employer as security against defects and incomplete work, creating a cumulative fund that is released in stages after completion. For the quantity surveyor, retention touches every interim valuation, every cash flow forecast, and every final account. Understanding how it works, when it is released, and the risks it creates is essential knowledge for both students and seasoned practitioners.

What Retention Is and Why It Exists

Retention is a cash deduction — typically 5% — applied to the gross value certified in each interim payment. The withheld money accumulates over the life of the contract, subject to a limit of retention (often 3–5% of the contract sum), beyond which no further deduction is made. The purpose is twofold: it provides the employer with a financial buffer to fund remedial works if the contractor fails to rectify defects, and it incentivises the contractor to complete the works and make good any snagging items promptly.

Retention differs from other forms of security such as performance bonds or parent company guarantees. Those instruments are third-party guarantees — the employer does not hold the contractor’s cash. With retention, the employer holds actual money, which directly reduces the contractor’s interim receipts and, by extension, the cash flow of every subcontractor and supplier in the chain below.

How Retention Is Released

Retention is released in two stages. The first moiety — 50% of total retention held — is released when the architect or contract administrator certifies practical completion. This recognises that the works are substantially complete and the employer has taken possession, even if minor defects remain. The second moiety — the remaining 50% — is released at the end of the defects liability period (DLP), typically 6–12 months after practical completion, once the architect has issued a making good certificate confirming that all notified defects have been remedied.

If defects remain outstanding at the end of the DLP, the employer may withhold all or part of the second moiety until they are resolved — or use the retained funds to employ others to carry out the remedial work.

JCT and NEC4: Different Approaches

Under JCT SBC 2024 and JCT DB 2024, retention is governed by Clause 4.16. The retention percentage and limit of retention are stated in the contract particulars, and the two-moiety release described above applies. The first release is included in the interim certificate following practical completion; the second follows the making good certificate issued under Clause 2.40.

Under NEC4 ECC, retention is optional and applied through secondary Option X16. The percentage is stated in the Contract Data. Unlike JCT, NEC4 does not split release into two moieties — retention is held in full until the Project Manager issues the Defects Certificate, typically at the end of the defect correction period (often shorter than JCT’s DLP). This single-release mechanism is simpler but means the contractor waits longer for the full amount. The QS should be alert to this difference when advising on cash flow under NEC contracts.

The Trust Problem

One of the most significant risks with retention is its legal status. Under current law, retention money is not held in trust unless the contract expressly provides otherwise. The principle established in Rayack Construction Ltd v Lampeter Investments Ltd (1958) is that retention belongs to the employer, who can use it for any purpose — including paying other creditors. Section 233 of the Housing Grants, Construction and Regeneration Act 1996 would have required employers to hold retention in trust, but this provision was never enacted.

The practical consequence is stark: if the employer becomes insolvent, the contractor loses the retention money. The contractor ranks as an unsecured creditor and typically recovers only a fraction — often 5–20p in the pound — in administration. This risk cascades down the supply chain: subcontractors and suppliers who have had retention withheld by the main contractor face the same exposure.

Alternatives to Cash Retention

Retention bonds are the most common alternative. The contractor procures a bond from an insurer or bank covering the retention amount, allowing the employer to release cash while maintaining equivalent security. The cost (typically 1–3% of bond value) is borne by the contractor but is usually recovered through improved cash flow. Project bank accounts (PBAs) offer another route: a neutral third party holds the retention, preventing the employer from using it for other purposes and protecting the fund in the event of insolvency. Retention deposit schemes and escrow accounts serve similar functions but with higher administration costs.

The QS should be familiar with all four options and be prepared to advise clients on the trade-offs between cost, administration, and risk protection.

Industry Reform

Retention reform has been a live campaign issue for over a decade. Build UK has long advocated for a statutory retention trust, and the Pye Tait research (2017) estimated that retention abuse costs the UK construction industry £8–12 billion annually through late release, non-release, and the cascading cash flow burden on SMEs. The Aldous Bill (2018) — a Private Member’s Bill proposing a statutory trust — did not progress through Parliament. As of 2026, retention reform remains a campaign objective rather than law, though larger projects increasingly adopt bonds or PBAs as standard practice.

The QS Role

The quantity surveyor’s responsibilities around retention span the full project lifecycle. At contract review, the QS checks the retention percentage and limit, assesses the employer’s creditworthiness, and advises on whether cash retention or an alternative mechanism is appropriate. During interim valuations, the QS maintains a retention register — tracking the amount withheld per certificate, cumulative retention held, and whether the limit has been reached — and audits the architect’s certificates for accuracy. At practical completion and DLP expiry, the QS diarises release dates, chases the architect for the making good certificate if delayed, and ensures the employer releases funds promptly. At final account, the QS reconciles total retention released against the contract particulars and resolves any discrepancies.

Common Problems and Practical Tips

Late release is the most frequent complaint — employers or their agents delay issuing the making good certificate, holding the second moiety well beyond the DLP. Employer insolvency remains a real risk, particularly for subcontractors further down the chain. Defects disputes can hold up the second moiety indefinitely if the parties cannot agree what constitutes a defect versus normal wear or a design issue.

Practical advice: always check the retention percentage and limit at contract review — do not assume 5% is standard. Maintain a retention register from day one and update it at every interim certificate. Diarise both the practical completion date and the DLP expiry as release milestones. For financially weaker employers, recommend a retention bond rather than cash retention. And at final account, reconcile retention released against the contract to ensure nothing has been missed.

APC Relevance

Retention maps directly to the RICS APC competencies of Contract Practice (understanding standard-form retention clauses, advising on alternatives, managing release) and Quantification and Costing (applying retention deductions in interim valuations, reconciling at final account, forecasting cash flow). APC candidates should be able to explain the two-moiety release mechanism, describe the trust status risk, and discuss when alternatives to cash retention are appropriate.

Further Reading on ProQS

For more on related QS skills, see these ProQS articles:

Interim Valuations and Payment Applications — how retention is deducted within the interim valuation process.

Construction Contracts Overview — the standard forms that govern retention mechanics.

Final Accounts and Settlement — how retention is reconciled at project close-out.

Financial Management in Construction — the cash flow implications of retention for contractors and employers.

Key References

Housing Grants, Construction and Regeneration Act 1996, s.233 — the proposed (but never enacted) statutory retention trust provision.

Designing Buildings Wiki: Retention in Construction Contracts — comprehensive reference covering retention mechanics, release, and reform.

Build UK: Retentions Campaign — the industry campaign for retention reform and statutory trust protection.

RICS: Interim Valuations and Payment — professional guidance covering retention within interim valuation best practice.

JCT Contracts — the Joint Contracts Tribunal, publisher of JCT SBC 2024 and DB 2024.