Introduction
If you work across JCT and NEC contracts, you will know that the two forms handle scope changes in very different ways. JCT uses variations. NEC uses compensation events. The underlying principle is the same: work has changed from what was originally contracted, and someone needs to be compensated. But the process, the timescales, and the commercial consequences are materially different.
Understanding compensation events vs variations in construction is not just a technical point. It affects how your commercial team manages entitlement, whether claims are accepted or time-barred, and ultimately how much margin is protected or lost on NEC projects.
This article explains the difference, where NEC and JCT diverge, and what commercial teams need to do differently when working under an NEC contract.
What Is a Variation (JCT)?
Under JCT contracts (Standard Building Contract, Design and Build, Minor Works, and others), a variation is any change to the works instructed by the Employer or their representative. The JCT definition of a variation typically includes:
- Alteration of the kind or standard of materials or goods
- Addition, alteration, or omission of any work
- Changes to access, working conditions, or sequence imposed by the Employer
The instruction must come from the right person, typically the Architect or Contract Administrator named in the contract. A variation instruction triggers an obligation to carry out the work and a right to be paid for it.
Valuation follows the hierarchy of contract rates, fair rates, and dayworks, as set out in the contract. Crucially, under JCT there is no absolute condition precedent requiring notification within a set time. The absence of a formal notification period means disputes are common but rarely fatal to the claim on procedural grounds alone.
What Is a Compensation Event (NEC)?
Under NEC contracts (NEC4 Engineering and Construction Contract, NEC3, and related forms), the equivalent mechanism is the compensation event. A compensation event is a defined event that gives the Contractor an entitlement to additional time and/or money.
The NEC contract lists the compensation events in clause 60. They include:
- The Project Manager giving an instruction to change the Works Information (the NEC equivalent of a variation instruction)
- The Employer failing to provide something they were obliged to provide
- Physical conditions encountered which an experienced contractor could not reasonably have anticipated
- The Project Manager giving an instruction to stop work or change the programme
- A number of other defined circumstances
The critical difference from JCT is the process. Under NEC, the Contractor must notify a compensation event within 8 weeks of becoming aware of it. This is a condition precedent. If the Contractor fails to notify in time, they lose the entitlement to additional time or money, even if the event is real and the costs are clearly recoverable.
This is not a technicality. It is a fundamental feature of the NEC philosophy, which requires early warning and collaborative management of risk. The time bar is enforced and it is enforced strictly.
The NEC Compensation Event Process
The compensation event process under NEC4 works as follows:
Step 1: Early warning (if applicable). If the Contractor is aware of any matter that could affect cost or programme, they are obliged to give an early warning notice. This is not the same as notifying a compensation event, but it is the starting point for collaborative management of issues.
Step 2: Notification. Within 8 weeks of becoming aware of the compensation event, the Contractor notifies the Project Manager. The notification identifies the event and requests a quotation. If the Contractor fails to notify within 8 weeks, the time bar applies.
Step 3: Project Manager instruction. If the Project Manager agrees that the event is a compensation event, they instruct the Contractor to provide a quotation. If they disagree, the Contractor can refer the matter to the dispute resolution process.
Step 4: Quotation. The Contractor submits a quotation within 3 weeks (unless a different period is agreed). The quotation must assess the impact on Defined Cost and on the programme.
Step 5: Assessment. The Project Manager assesses the quotation within 2 weeks of receiving it. They may accept it, propose changes, or make their own assessment if the Contractor's quotation is not submitted on time.
Step 6: Implementation. Once agreed or assessed, the compensation event is implemented by adjusting the Prices and the Completion Date.
The process is more structured and more time-sensitive than JCT. Miss a step and the consequences are commercial, not just procedural.
Key Commercial Differences
| JCT Variation | NEC Compensation Event | |
|---|---|---|
| Trigger | Instruction from Architect/CA | Instruction from Project Manager or defined event |
| Notification | No absolute time bar | 8-week condition precedent |
| Valuation method | Contract rates, fair rates, dayworks | Defined Cost (Schedule of Cost Components) |
| Time entitlement | Extension of time under relevant events | Built into the compensation event quotation |
| Pricing basis | Retrospective (after the work) | Prospective (forecast at time of quotation) |
| Who assesses | QS for both parties | PM assesses if Contractor does not quote in time |
The prospective pricing approach under NEC is particularly significant. Under JCT, you typically value a variation after the work is done, using actual records. Under NEC, the expectation is that you forecast the cost impact at the time of the event. If you wait until the project is complete to identify and price compensation events, you are working against the grain of the contract and likely against the clock.
For more on how valuation works under both contract forms, see How to Value a Variation in Construction.
NEC on Subcontracts
Many subcontracts in the UK market use JCT or bespoke forms even when the main contract is NEC. This creates a mismatch: the main contractor is running a compensation event process upstream but managing subcontractors under a different regime downstream.
This matters because the timescales do not align. If the main contractor has 8 weeks to notify a compensation event to the Project Manager, but their subcontract does not impose equivalent timescales on the subcontractor, the main contractor may receive a subcontractor claim long after the main contract window has closed.
A commercial team that understands both regimes, and manages the interface between them, has a significant advantage over one that treats them as equivalent.
Common Mistakes on NEC Projects
- Treating compensation events like JCT variations and failing to notify within 8 weeks
- Not giving early warning notices for issues that could become compensation events
- Submitting quotations late and losing the right to have them assessed
- Quoting retrospectively (actual costs) rather than prospectively (forecast costs)
- Failing to track the Project Manager's response deadlines (if the PM does not respond in time, the event may be treated as accepted)
- Not linking NEC compensation events to downstream subcontract claims
StoneRise Commercial manages variation and compensation event workflows with automated deadline tracking, so your commercial team never misses a notification window or quotation deadline regardless of whether the contract is JCT or NEC.
Conclusion
The difference between a compensation event and a variation is not just terminology. NEC's structured, time-sensitive process is fundamentally different from JCT's more flexible approach. Missing an 8-week notification deadline under NEC is not the same as submitting a variation claim a few weeks late under JCT. Under NEC, the entitlement is gone.
Commercial teams working across both contract forms need clear processes for each, and the discipline to follow them even when the project is under pressure.
Managing NEC and JCT projects without missing a deadline?
StoneRise Commercial tracks compensation event and variation deadlines across all contract types, keeping your commercial position protected on every project.
Frequently Asked Questions
What is a compensation event in NEC? A compensation event is the NEC contract mechanism for dealing with changes and other defined events that entitle the Contractor to additional time and/or money. It is the NEC equivalent of a variation instruction under JCT, but with a more structured process and strict notification timescales.
What is the 8-week rule in NEC? Under NEC4 (clause 61.3), the Contractor must notify a compensation event within 8 weeks of becoming aware of it. Failure to notify within this period is a condition precedent: the entitlement to additional time or money is lost.
Can you use dayworks under an NEC contract? NEC contracts do not use dayworks in the traditional sense. Compensation events are assessed using Defined Cost (based on the Schedule of Cost Components), which is different from dayworks but serves a similar purpose of capturing actual resource costs when other valuation methods are not applicable.
What happens if the Project Manager does not respond to a compensation event notification? Under NEC4, if the Project Manager does not respond to a Contractor's notification within the required period, the Contractor can notify the Project Manager that they have not responded. If the Project Manager still does not respond within a further 2 weeks, the compensation event is treated as accepted (clause 61.4).
Are compensation events and variations the same thing? No. Both deal with changes to the scope or circumstances of a contract, but they operate under entirely different processes. JCT variations use retrospective valuation with no absolute notification time bar. NEC compensation events use prospective pricing with a strict 8-week condition precedent for notification.
