The main difference in NEC vs JCT is when problems get dealt with. NEC expects cost and time effects to be priced and settled close to the event, against a live programme, whereas JCT more often settles delay and loss after the effect is known. JCT remains the familiar choice for UK building work, while NEC is common on public sector and infrastructure jobs.
This is a comparison of the published forms in general. NEC references are to the NEC4 Engineering and Construction Contract (ECC). JCT has many versions, and clause arrangements vary between them, so check your own edition. More comparisons are in our guide to NEC and other contracts.
Side by side
| Topic | NEC4 ECC | JCT (typical main forms) |
|---|---|---|
| Choosing the form | One contract, with a main Option chosen for how the Contractor is paid | A separate contract for each size or type of job, such as minor works, intermediate, standard and design and build |
| Contract manager | Project Manager, with a Supervisor for quality | Architect or Contract Administrator, or an Employer's Agent on design and build; often with a Quantity Surveyor |
| Change and client-side events | All handled as compensation events, which deal with price and time together | Variations are valued; delay and direct loss and expense follow their own routes |
| Warning of problems | Either side gives an early warning (15.1), recorded on a register and worked through at meetings | Notices about delay and loss are central; any collaborative provisions depend on the form and edition |
| Programme | A detailed Accepted Programme, regularly revised and used to assess delay (31, 32, 63.5) | Usually a much lighter requirement, and less central to entitlement |
| Late notice | Contractor's notification can be time-barred after eight weeks, with exceptions (61.3) | Notice is required, but standard forms have generally been less stark about losing entitlement |
| Pricing of change | Effect on forecast and actual Defined Cost, plus the Fee (63.1) | Commonly by reference to contract rates and prices, where they apply |
| Language | Short sentences in the present tense, with many defined terms | More traditional legal drafting, and widely known across UK building |
One late design change under each form
Take a fictional office fit-out, with illustrative figures. In week 10, the client changes the specification for a partition. It adds work and stops one trade for a week.
Under NEC4 ECC, Option A
- The Project Manager instructs the change and notifies a compensation event under 60.1(1), asking for a quotation.
- The Contractor has three weeks to send its quotation, showing forecast Defined Cost plus the Fee, and the effect on planned Completion from the Accepted Programme (62.2, 62.3).
- The Project Manager has two weeks to respond. If it accepts, for example at £12,000 and four days, the Prices and Completion Date change. That assessment is then normally closed, even if the actual cost turns out differently (66.3).
Under a typical JCT form
- The Architect or Contract Administrator issues an instruction, which is a variation.
- The Quantity Surveyor values the added work, usually with the rates in the contract where they apply.
- The Contractor gives notice of delay. The administrator decides whether to grant an extension of time, and that decision may come well after the event.
- Any direct loss and expense from the disruption is claimed and ascertained separately, and may stay open until the final account.
Neither route is automatically fairer. NEC asks for more work up front and provides early certainty, but a forecast might be wrong. JCT's approach can reflect what actually happened, although the final figure may stay open for longer.
What to watch when moving between them
- From JCT to NEC: you can't hold back a claim until the final account. Set up a routine for the 61.3 notification period from day one.
- From NEC to JCT: don't expect a failure to reply to resolve things for you. NEC4's deemed acceptance after a further notified failure is specific to NEC (61.4, 62.6, 64.4 and, for programmes, 31.3).
- Either way: don't carry defined terms across. Completion, Defect and Prices all have specific meanings in NEC. The table of JCT terms in NEC language gives the closest matches.
Which to choose
NEC tends to suit clients who will resource active management, work with real uncertainty, or want a target or cost-based option under one family of contracts. JCT tends to suit building work where the team knows the form, the design is well developed and the client wants a conventional process. Clients weighing this up can read the difference between JCT and NEC for clients, and those leaning towards NEC should look at how to choose a main Option.
Related guides
- NEC vs Other Construction Contracts
- Difference Between JCT and NEC for Clients
- JCT Terms in NEC Language
- NEC vs FIDIC
See how this works in practice
Click through Contract Status with sample contracts: raise the notice, reply to it, and watch both sides of one record.
Take the guided tour Book a demo
Use the contract picker, use the free NEC tools or download free NEC templates.
This guide is general information in our own words, not legal advice. Your contract and its Contract Data always govern. NEC, NEC3 and NEC4 are trade marks of Thomas Telford Ltd; Contract Status is not affiliated with or endorsed by NEC.