If you're a subcontractor working on UK construction projects, the contract you sign is almost certainly a JCT contract — or based on one. The Joint Contracts Tribunal publishes the standard forms used on around 70% of all UK construction projects, and in 2024 they released a completely updated suite of contracts for the first time since 2016.
What's changed matters to you. Some changes are genuinely beneficial for subcontractors. Others require careful attention. And the transition has created a new risk — main contractors are issuing amended JCT 2024 contracts with changes that favour them, and many subcontractors are signing without realising anything has shifted.
Why the JCT Updated Its Contracts
The JCT publishes new editions periodically to reflect changes in the law, industry practice, and lessons learned from disputes. The 2024 suite was the most significant update in eight years, driven by several factors:
- The Carillion collapse in 2018 exposed serious weaknesses in how retention was handled and how subcontractors were protected when main contractors became insolvent
- The Building Safety Act 2022 introduced significant new requirements around building safety that needed to be reflected in contract terms
- The Construction Act and payment legislation had evolved in ways the 2016 contracts didn't fully reflect
- Industry feedback identified areas where the standard terms were creating unnecessary disputes
The Key Changes — What You Need to Know
1. Retention — Better Protection But Only If It's in Your Contract
The issue of retention has been one of the most contentious in construction for years. Billions of pounds in retention money is tied up across the industry at any one time, and subcontractors lose significant sums every year when main contractors become insolvent before releasing it.
The JCT 2024 has responded to this in two important ways. First, the standard retention rate has been reduced from 5% to 3% in the updated forms. Second, there is greater emphasis on the timing and mechanism of retention release.
The 3% standard rate only applies if your contract uses the JCT 2024 standard terms without amendment. Many main contractors are issuing amended contracts that retain the old 5% rate. Always check what percentage your specific contract states — don't assume it's the standard.
What hasn't changed is that there is still no mandatory requirement to protect retention money in a trust account or bond. This means that if your main contractor becomes insolvent while holding your retention, you remain an unsecured creditor — which in practice means you're unlikely to get it back. Always consider asking for a retention bond on high-value contracts.
2. Payment Notices — Tighter Timescales
The payment provisions in JCT 2024 have been updated to reflect the current requirements of the Construction Act. The key points for subcontractors are:
- The main contractor must issue a Payment Notice within a specified period of the payment due date — failure to do so means your application becomes the notified sum automatically
- Pay-less notices must be issued within a specific window before the final date for payment
- The JCT 2024 standard sets this pay-less notice window at 5 days before the final date for payment
Watch out for contracts that have amended this window to 3 days or fewer. This is a common amendment that significantly reduces your ability to respond if a pay-less notice is issued. Three days — often over a weekend — is not enough time to take advice and respond effectively.
Set calendar alerts for every payment due date on every contract. Missing a pay-less notice deadline — even by one day — can mean you lose the right to dispute a deduction entirely.
3. Building Safety Act Integration
The Building Safety Act 2022 introduced a new regulatory framework for higher-risk buildings — primarily residential buildings over 18 metres or 7 storeys. If you're working on projects that fall within this regime, the JCT 2024 contracts include provisions that affect how work is documented, how changes are instructed, and how completion is defined.
For most SME subcontractors working on commercial and lower-rise residential projects, the practical impact is limited. But if you're working on high-rise residential projects, it's worth understanding how the Building Safety Act affects your obligations under the contract.
4. Termination Provisions — Read These Carefully
The JCT 2024 has updated its termination provisions to clarify the rights of both parties. The standard form provides reasonable protections for subcontractors in the event of termination — including the right to payment for work done and loss of profit on the remaining contract.
Many main contractors add a termination for convenience clause to their subcontracts — allowing them to end the contract at any time with short notice and no reason given. This is not in the standard JCT 2024 subcontract. If you see this clause, it is a non-standard amendment that significantly increases your risk.
5. Dispute Resolution — Your Rights Are Preserved
One genuinely positive aspect of the JCT 2024 is that your statutory right to adjudication is clearly preserved. Adjudication is a fast, relatively affordable dispute resolution process available to all construction subcontractors under the Housing Grants, Construction and Regeneration Act 1996.
Your right to refer a dispute to adjudication at any time cannot be removed by the contract. It is a statutory right. If you're in a payment dispute, adjudication typically produces a decision within 28 days and is far cheaper than litigation.
The JCT 2016 Withdrawal — What It Means for You
JCT 2016 editions were formally withdrawn from sale on 31 March 2026. This means that going forward, all new JCT contracts should be issued using the 2024 editions. However, contracts signed before that date under JCT 2016 terms remain valid and continue under those terms until completion.
In practice this means the industry is currently in a transition period. It's important to know which version you're being asked to sign — and to understand that the two editions have meaningful differences.
The Biggest Risk Right Now — Non-Standard Amendments
The single biggest risk for subcontractors during this transition is not the changes in JCT 2024 itself — it's the amendments that main contractors are adding on top of the standard form.
Common non-standard amendments we see include:
- Retention rates increased from the 3% JCT 2024 standard to 5% or higher
- Pay-less notice windows shortened from 5 days to 3 days or fewer
- Termination for convenience clauses added — not in the JCT standard
- Fitness for purpose obligations added — a much higher standard than reasonable skill and care
- Back-to-back clauses that pass down onerous main contract terms without clearly identifying them
- Extension of time mechanisms that are vague or heavily time-barred against the subcontractor
What to Do Before You Sign
- Read the contract in full, including all schedules and appendices. Don't just check the commercial terms.
- Identify whether you're being asked to sign a standard JCT form or an amended version. If it's amended, note every change.
- Pay particular attention to payment terms, retention, LADs, and termination clauses.
- If you identify concerns, raise them before you sign. Most main contractors will negotiate — especially if you can point to the JCT standard as your reference.
- For high-value contracts or contracts with multiple non-standard amendments, consider getting a professional review before signing.
Review your JCT subcontract before you sign — in minutes, not days.
Join the Waiting List at kontrak.co.uk →