Concurrent Delay: Win It in Month 3, Not Month 30

Concurrent delay: the argument you win in month three, not month thirty

7 min read · Dr. Sriniwasa Prabhu N · Founder & Managing Director · Project Assure · 2026

Windows analysis can only separate employer and contractor causation if the contemporaneous programme updates actually captured both. That work happens in month three, or not at all.

In short

Concurrent delay is where an employer-risk event and a contractor-risk event both affect the same period of critical delay. A windows (time-slice) analysis can only separate the two causes if the contemporaneous programme updates captured both, with logic, fragnets and notices matching the events. That record is built within the notice period, not reconstructed later.

Concurrent delay, where an employer-risk event and a contractor-risk event both affect the same period of critical delay, is one of the most contested areas in construction disputes. But by the time it reaches a tribunal, the outcome is largely determined by records created years earlier.

Why is concurrency fought late but lost early?

The analysis that resolves concurrency (typically a windows (time-slice) analysis) can only separate employer and contractor causation if the contemporaneous programme updates actually captured both: with logic, with fragnets, with notices that match the events. If the month-by-month record is thin, the expert is reconstructing causation years after the fact, and reconstruction is expensive and contestable.

Entitlement preserved is negotiating leverage. Entitlement reconstructed is an expert-witness fee.

What does the SCL Protocol expect on concurrency?

The Society of Construction Law Delay and Disruption Protocol is clear that the strongest position rests on contemporaneous analysis, assessing the impact of events as they occur, against an accurate updated programme. Its guidance on concurrency (that where true concurrency exists, a contractor may be entitled to time but not necessarily to prolongation cost) can only be applied if the record supports a clean separation of causes in the first place.

What is the month-three discipline?

The engagements that resolve early share one habit: every delay event gets characterised within the notice period, even when the impact is not yet quantifiable. That means:

A dated notice that matches a real event on the programme.
A fragnet showing the logic of the impact, inserted into the current update.
A contemporaneous view of what else was critical at the same time, the raw material of any future concurrency argument.

None of this requires knowing how the dispute will end. It requires a record good enough that the answer is already in the data when the question is finally asked.

How do you make the month-three discipline cheap?

The reason the month-three discipline is so often skipped is that it feels expensive against day-to-day delivery pressure. It should not be. Our Progress Intelligence platform captures the contemporaneous record: progress, resources, QA and events, at source, and our forensic delay and claims team structures entitlement while it is still cheap to preserve. The month-three habit is what makes the month-thirty dispute unnecessary.

Common questions

What is concurrent delay in construction?

Concurrent delay is where an employer-risk event and a contractor-risk event both affect the same period of critical delay. It is one of the most contested areas in construction disputes, but by the time it reaches a tribunal the outcome is largely determined by records created years earlier. Reconstruction after the fact is expensive and contestable.

What does the SCL Protocol say about concurrent delay?

The Society of Construction Law Delay and Disruption Protocol is clear that the strongest position rests on contemporaneous analysis: assessing the impact of events as they occur, against an accurate updated programme. Its guidance on concurrency, that where true concurrency exists a contractor may be entitled to time but not necessarily to prolongation cost, can only be applied if the record supports a clean separation of causes.

What records do I need to preserve a concurrent delay argument?

Three things, within the notice period for every delay event: a dated notice that matches a real event on the programme; a fragnet showing the logic of the impact, inserted into the current update; and a contemporaneous view of what else was critical at the same time, which is the raw material of any future concurrency argument.

Why is a concurrent delay argument lost early in a project?

Because the analysis that resolves concurrency, typically a windows (time-slice) analysis, can only separate employer and contractor causation if the contemporaneous programme updates actually captured both. If the month-by-month record is thin, the expert is reconstructing causation years after the fact, and reconstruction is expensive and contestable.

Bring this discipline onto your programme.

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