What are the JCT retention release rules? Under unamended JCT Design and Build Subcontract conditions (DBSub/C Clause 4.18), retention is released in two equal stages: the first 50% upon practical completion of your subcontract works, and the remaining 50% following the expiry of the Rectification Period and resolution of defects. Bespoke amendments frequently link release to upstream main contract milestones, causing severe subcontract revenue loss.
Retention deductions are intended to provide security against defective workmanship. In commercial practice, unreleased retention balances represent trapped profit margins that contractors routinely defer for years after you leave the site.
Under standard JCT Design and Build Subcontracts (DBSub/C), retention release mechanics are set out in Clause 4.18. Identifying whether your subcontract links retention release to your own package or to the wider main contract project is essential to protect your cash flow.
1. Technical Authority: Clause 4.18 Subcontract Mechanics
In standard unamended JCT DBSub/C 2016/2024 forms, retention deduction and release follow a precise mechanism:
- Retention Percentage (Clause 4.18.1): The agreed percentage (standardly 3% or 5%) is deducted from interim valuations up to practical completion of the subcontract works.
- First Release (Clause 4.18.2): Upon practical completion of the subcontract works, the retention percentage applied to interim payments is halved (typically from 3% to 1.5%, or 5% to 2.5%), releasing the first tranche in the subsequent interim payment.
- Second Release (Clause 4.18.3): The remaining retention balance is released in the interim payment following the expiration of the Rectification Period specified in the Sub-Contract Particulars and the completion of making good defects in your subcontract works.
- Statutory Notice Separation: If a main contractor intends to withhold retention release, they must issue a compliant Pay Less Notice under Clause 4.7 specifying the grounds and calculation. Without a valid notice, the sum remains payable under Section 111.
2. Common Retention Amendments Encountered in Practice
Commercial teams frequently alter standard retention mechanics through bespoke Schedules of Amendments:
- The Upstream Certification Trap: Amending Clause 4.18.3 so that the final release is conditional upon the issue of the Notice of Completion of Making Good Defects under the Main Contract, rather than your specific subcontract package. This can trap your funds for years while unrelated trades complete their snagging.
- Conditional Payment Mechanics: Clauses that make release conditional on the employer releasing retention to the main contractor. Such terms must be evaluated against Section 113 of the Construction Act, which outlaws conditional payment mechanisms except in specific cases of upstream insolvency.
- Extended Rectification Periods: Increasing the standard 12-month Rectification Period to 24 or 36 months, compounding financial exposure and borrowing costs.
Is a Contractor Withholding Due Retention on an Invalid Notice?
Contractors cannot block retention payments with uncalculated assertions. If a Pay Less Notice fails to detail the actual basis of calculation under Section 111, challenge it immediately.
Check Pay Less Notice Validity →3. Commercial Impact: The Cost of Trapped Working Capital
Accepting amended retention provisions creates significant commercial risk for trade contractors:
- Working Capital Depletion: A 5% retention deduction frequently represents the entire net profit margin on a trade package. Deferring its recovery compromises balance sheet liquidity.
- Insolvency Exposure: Retention funds held in a main contractor’s general account are unsecured. If an upstream contractor enters administration before your second-half retention falls due, those funds are almost entirely unrecoverable.
- Administrative Abandonment: The longer the release timeline is stretched, the harder it becomes to recover paperwork, verify site records, and secure sign-offs from personnel who have moved projects.
Frequently Asked Questions: Subcontract Retention Rules
When is retention released under JCT DBSub/C 2016?
Under unamended JCT DBSub/C Clause 4.18, the retention percentage is standardly halved upon practical completion of the subcontract works. The remaining retention is released following the expiration of the Rectification Period and the issue of the certificate or notice of completion of making good defects for the subcontract works.
Can a main contractor tie subcontract retention release to the main contract certificate?
Some bespoke amendments attempt to link second-half retention release to the Main Contract Notice of Completion of Making Good Defects. This practice can be challenged under Section 113 of the Construction Act if it operates as a conditional payment mechanism linked to third-party certifications.
What can a subcontractor do if retention is withheld past the due date?
If retention is due and the contractor has not served a timely, compliant Pay Less Notice under Clause 4.7 and Section 111 of the Construction Act, the notified retention sum is payable in full.
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