Subcontractors · Mandatory · Pre-Construction

Subcontract Agreement

A formal agreement between the principal contractor and subcontractor covering scope, payment terms, programme, and H&S obligations.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. Contract Law / Housing Grants Act remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Legal basis	Contract Law + Housing Grants Act 1996 + CDM 2015
Why in writing	Verbal construction contracts are legally valid but practically unenforceable — scope disputes, payment disputes, and completion disputes cannot be resolved without written evidence. The Housing Grants Act requires written contracts to include payment and adjudication provisions.
Standard forms	JCT Design and Build Subcontract (DBSub 2016): where subcontractor has design responsibility. JCT Intermediate Subcontract (ICSub 2016): most common for trade packages. NEC4 Short Subcontract: used where main contract is NEC4.
Key provisions	Scope; price and payment; programme; variations; defects liability; insurance; CDM responsibilities; dispute resolution (adjudication mandatory); termination; retention.
Retention	Retention is common in UK construction — typically 3-5% of contract sum. Half released on practical completion; balance on defects liability period expiry (typically 6-12 months).

1. The Subcontract Agreement — The Legal Foundation of the Relationship

The subcontract agreement is the legal document that governs the entire subcontract relationship — scope, payment, programme, obligations, and dispute resolution. In a dispute, the contract is what determines who is right. A well-drafted subcontract protects both parties; an absent or poorly drafted one creates expensive uncertainty. The single most effective risk mitigation for subcontract management is having a properly drafted, signed subcontract before work begins.

The Housing Grants, Construction and Regeneration Act 1996 (as amended by the Local Democracy, Economic Development and Construction Act 2009) imposes mandatory terms on all construction contracts — the right to payment in instalments, payment notices, pay-less notices, the right to suspend for non-payment, and adjudication within 28 days.

Standard form subcontracts (JCT, NEC) are well worth using — they provide tested legal frameworks that protect both parties

Bespoke construction subcontracts written without legal input frequently contain gaps, ambiguities, or provisions that would not withstand legal scrutiny. The JCT and NEC standard forms have been developed over decades, tested in courts, and are understood by contractors and subcontractors alike.

2. Subcontract Agreement — Key Provisions

Provision	Detail
Parties	PC and subcontractor legal names. Registered addresses.
Works	Precise scope by reference to drawings, specifications, schedules.
Contract sum	Fixed / remeasure / schedule of rates. Basis for payment.
Payment	Payment cycle (monthly applications standard). Payment notice timing. Pay-less notice rights. Final date for payment.
Retention	Rate (typically 3-5%). Release conditions. Defects liability period.
Programme	Commencement date. Completion date. Liquidated damages for delay.
Variations	Valuation basis. Approval required before instructed variation executed.
H&S obligations	CDM responsibilities. RAMS obligations. Compliance with site rules.
Insurance	Required levels. Provision of certificates.
Defects	Defects liability period. Obligation to rectify defects.
Adjudication	Mandatory — Housing Grants Act 1996. 28-day decision period. Binding until revision by arbitration/court.
Termination	Grounds for termination. Notice periods. Consequences.

Common Mistakes

Starting without a signed contract — relying on letters of intent

Letters of intent authorise limited preliminary work only. They are not a substitute for a full subcontract. Work proceeding beyond the LoI scope creates contractual uncertainty.

Using outdated contract forms

JCT forms are updated periodically. Using a 2005 or 2011 edition when a 2016 or later edition exists means missing legal and industry updates. Always use the current edition.

Poorly drafted bespoke conditions that override standard terms inconsistently

Bespoke special conditions added to standard forms that conflict with the standard terms create ambiguity. Bespoke amendments should be drafted carefully and with legal input.

Retention not held in trust

Retention money deducted from subcontractors remains the subcontractor’s money. Where a PC becomes insolvent, subcontractors lose retention unless it is held in a separate trust account.

No liquidated damages clause for delay

A subcontract without a liquidated damages clause means the PC must prove actual loss if the subcontractor delays completion — which is complex and uncertain.

3. Frequently Asked Questions

What is adjudication and when does it apply?▾

Adjudication is a rapid 28-day dispute resolution process mandatory in all UK construction contracts under the Housing Grants Act 1996. Either party can refer any dispute to a specialist adjudicator at any time. The decision is binding immediately and enforceable through the courts.

What are the Housing Grants Act payment notice requirements?▾

The Act requires: a payment notice within 5 days of the payment due date; a pay-less notice served at least 7 days before the final date for payment. If no payment notice is served, the subcontractor’s payment application becomes the notified sum and must be paid.

What is the defects liability period?▾

The defects liability period (DLP) is the period after practical completion during which the contractor is obliged to return to rectify any defects. Typically 6-12 months. The second half of retention is released at the end of the DLP.

Can a subcontract exclude the right to suspend for non-payment?▾

No. The right to suspend work for non-payment is a statutory right under the Housing Grants Act — it cannot be contracted out of. Any term that purports to remove this right is void.

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