Mace v Baltic [2026] EWHC 976 (TCC), handed down on Tuesday, settled a question that had remained open since Walter Lilly: can an adjudicator overturn a prospective extension of time? The answer is yes - but only by performing the same prospective exercise the original assessor was required to perform, working from the information that existed at the time. The case was decided on a JCT Design and Build contract. The principle reaches every Subcontractor running NEC.

The question Mace put to the court

Mace argued a bold position. An extension of time granted prospectively under clause 2.25.1 of the JCT D&B form is fixed at the moment it is given. Neither an adjudicator nor the court can review it, because neither can recreate the conditions of a prospective exercise the contract requires. The Employer's Agent had granted Mace seven weeks and five days. An adjudicator had reviewed that decision and reduced it to zero. Mace asked the TCC to declare that the adjudicator had no power to do so.

Adrian Williamson KC disagreed. The adjudicator can open up, revise and review the EOT under paragraph 20 of the Scheme for Construction Contracts. But - and this is where the judgment does its real work — in doing so, he must stand in the shoes of the Employer's Agent at the time the notice and particulars were submitted. The adjudicator carries out the same prospective task the contract assigns to the original assessor. He travels back to the date of the notice. He ignores what happened afterwards.

What Walter Lilly left implicit

Walter Lilly v DMW established that the JCT extension of time machinery required a prospective assessment of delay during the works, not a wholly retrospective exercise. The case left an awkward question hanging. If the original prospective assessment was wrong - perhaps badly wrong - what happens when a tribunal looks at it later, when the events have already played out and the answer is known?

Mace v Baltic answers it. Prospective methodology is not a one-off right that locks in a wrong answer at the moment of decision. When an adjudicator later reviews that EOT, they do not switch to a retrospective look-back just because they are operating after the fact. They are bound to use the same prospective method, working from the information that existed at the time of the original notice.

That is a more demanding standard than it first appears. The adjudicator is not asked to ratify the original decision. He is asked to redo it - properly - using only the evidence that was available when it was first made.

Why this reaches NEC

Mace v Baltic is a JCT case. The contractual route to the same conclusion under NEC is not identical, but the destination is.

Under the NEC Engineering and Construction Subcontract, Clause 63 governs the assessment of compensation events. The assessment of time and cost is forward-looking from the dividing date - the date the compensation event was notified, whether by the Subcontractor under Clause 61.3 or by the Contractor. Everything before the dividing date counts as fact. Everything after it is forecast.

If the principle in Mace v Baltic applies - and there is no obvious reason it should not - an adjudicator reviewing a Clause 63 assessment is doing the same job Williamson KC described. Standing in the Subcontractor's shoes at the dividing date. Working with the information available then. Ignoring what happened afterwards.

That changes the character of the notice and the quotation. They stop being procedural housekeeping. They become the evidential foundation of every future challenge.

What this means for live contracts

For a T2 or T3 Subcontractor running multiple NEC subcontracts across a portfolio, the implication is direct.

Every CE notification, every quotation, every supporting particular submitted at the dividing date is the record the adjudicator will work from if the assessment is later disputed. Not the record built up afterwards in correspondence. Not the witness statement reconstructing what was known at the time. The contemporaneous notice and the particulars that accompanied it.

Thin particulars, thin defence. Robust particulars, protected entitlement.

This puts a sharper edge on a problem most subcontract commercial teams already know they have. Notices go out late. Particulars go out thin. Quotations are submitted with the time and cost numbers but without the underlying evidence that would let a future adjudicator agree with them on a prospective basis. The team intends to build the file later if the CE becomes contentious. Mace v Baltic shows that the file built later is the wrong file.

The discipline question

Mace v Baltic raises the bar. The harder question is whether your team can clear it on every contract, for every CE, for every notice.

Not the difficult ones. Not the high-value ones. Every one of them.

That is not a knowledge question. Most subcontract commercial teams know what a good CE notification looks like. It is a habits and systems question. It is the difference between reactive firefighting and disciplined routines your team runs every day, on every contract, without needing to be told.

A well-administered NEC subcontract does not need its team to remember what to do when a CE arises. It runs the routine. The notice goes out on time. The quotation is supported by particulars sufficient to satisfy the prospective assessment standard. The record is built at the dividing date, not after.

Mace v Baltic is the latest reason to take that discipline seriously. It will not be the last.

 

 

Best, Radek Makar Director | ViViAD radek@viviad.co.uk

ViViAD is an independent consultancy specialising in Planning, Project Controls, Power BI Reporting, and Construction Claims Support. We work across the UK - typically on NEC contracts in defence, nuclear, renewables, and infrastructure - embedding with project teams to bring structure, clarity, and commercial control. Interim or longer-term, we fit around what you need.