Concurrent Delay: How It Affects Your Time and Money Entitlement

Concurrent delay is where contractors lose entitlements they genuinely hold, not because the delay was not real, but because they misunderstood how time and money behave when two causes overlap. The instinctive view is that if the employer caused a delay and the contractor caused a delay at the same time, the two simply offset and nobody owes anybody anything. That instinct is wrong, and acting on it costs contractors both the extension of time they were entitled to and, occasionally, exposure to liquidated damages they could have avoided. The single most important thing to understand about concurrent delay is that time and money are decided by different tests, and they frequently give different answers.

The reason this matters commercially is straightforward. An extension of time protects you from liquidated damages. Prolongation cost recovery protects your margin. These are two separate entitlements decided by two separate questions, a distinction we set out in full in EOT vs Prolongation. Concurrent delay is the situation where those two entitlements most often diverge: you win the time and lose the money. A contractor who does not grasp that divergence will either fail to claim the time it is owed or wrongly assume that winning the time guarantees the cost. Both errors are avoidable.

What Concurrent Delay Actually Is

True concurrent delay, in the strict sense, is the situation where two or more delay events occur at the same time, each of which would independently have caused critical delay to completion, and where one is at the employer's risk and the other is at the contractor's risk. The classic illustration is a two-week period in which the employer has failed to provide access to a critical work area while, over the very same two weeks, the contractor's own labour shortage would independently have prevented progress on that same critical activity. Neither party could have completed on time during that window even if the other's delay had not existed.

The strict definition matters because the word concurrent is used loosely on site to describe any two things going wrong at once. Genuinely concurrent critical delay is rarer than the everyday usage suggests. Much of what is called concurrency is in fact sequential delay, where one cause is on the critical path and the other is not, or where the two causes affect different activities and only one is actually driving the completion date. The analytical discipline is to establish which delay was truly critical, over which period, and whether a competing cause was genuinely critical during the same window. This is why the choice of delay analysis method matters so much, a subject we cover in Delay Analysis Methods Explained. Get the criticality analysis wrong and the concurrency argument is built on sand.

Why Time and Money Are Decided Differently

The heart of concurrent delay is that the entitlement to time and the entitlement to cost are governed by different principles. Extension of time is generally decided by a causation test that asks whether an employer risk event caused critical delay to completion. Prolongation cost, by contrast, is generally decided by a test that asks whether the contractor actually incurred additional cost as a result of an employer risk event, and whether that cost would have been incurred anyway because of a concurrent contractor delay.

The prevailing approach in much of international construction practice, reflected in the Society of Construction Law Delay and Disruption Protocol, is that where an employer delay and a contractor delay are truly concurrent, the contractor is entitled to an extension of time for the period of concurrency but is not entitled to recover the prolongation cost of that period. The logic is that the extension protects the contractor from liquidated damages for a delay that was, in part, the employer's responsibility, but the contractor should not recover time-related costs it would have incurred in any event because of its own concurrent delay. In other words, the contractor keeps the time but not the money. This is not a quirk. It is the deliberate result of applying a causation test to time and a but-for cost test to money.

It is important to note that this is an area where the law differs between jurisdictions and where the specific wording of the contract can change the outcome. Some contracts expressly allocate concurrency risk. Some legal systems approach the apportionment of concurrent delay differently. The general principle above is the common starting point in FIDIC-based international practice, but it is a starting point, not a universal rule, and the applicable law and contract terms must always be checked.

The Trap: Assuming Concurrency Cancels Everything Out

The most damaging misconception is the belief that concurrent delay is a wash, that because both parties contributed, neither has any entitlement and the safest course is to say nothing. This is wrong in both directions. It is wrong because the contractor usually does have an entitlement to time during a period of genuine concurrency, and failing to claim it leaves the contractor exposed to liquidated damages for a delay that was partly the employer's responsibility. And it is wrong because the belief encourages contractors to stay silent, to not issue notices, and to not keep the contemporaneous records that a concurrency analysis depends on.

The practical consequence of the wash assumption is that contractors under-claim. They see their own delay running alongside the employer's, conclude they have no case, and never notify the employer delay at all. Then, at the end of the project, the employer levies liquidated damages for the full overrun, and the contractor discovers too late that a properly notified and analysed concurrency argument would have secured an extension of time covering a substantial part of that overrun. The entitlement existed. The silence destroyed it. The discipline that prevents this is the same notice discipline that governs every other time-sensitive entitlement, which we examine in The 28-Day Rule.

What This Means for Your Records and Notices

Concurrent delay is won or lost on the quality of the contemporaneous programme records, because the entire argument turns on establishing what was critical, when, and why. The contractor who wants to preserve its concurrency position must do three things from the outset. First, maintain a properly updated programme that shows the critical path and how it moves as the project progresses, so that the criticality of each delay event can be demonstrated rather than reconstructed. Second, notify every employer risk event as it arises, regardless of whether a contractor delay is also running, because the right to an extension of time depends on the notice being given. Third, keep the cause-specific records that allow an analyst to separate the employer delay from the contractor delay, since a concurrency argument that cannot distinguish the two causes will fail. Where a concurrency dispute has already crystallised, independent forensic delay analysis is what resolves it, and that forensic capability is the core of CALIM's delay analysis and dispute support.

The contractor should also resist the temptation to overstate concurrency in its own favour. Tribunals and engineers are alert to the tactic of labelling every contractor delay as concurrent with some employer event in order to escape liquidated damages. A concurrency argument that does not stand up to a criticality analysis damages the contractor's credibility on the rest of the claim. The honest position, supported by the records, is far stronger than an aggressive position that collapses under scrutiny. Where the analysis genuinely supports concurrency, claim the time confidently. Where it does not, do not manufacture it.

Frequently Asked Questions

What is concurrent delay in construction?

Concurrent delay, in the strict sense, is where two or more delay events happen at the same time, each of which would independently have caused critical delay to completion, and where one is at the employer's risk and the other is at the contractor's risk. During that period neither party could have completed on time even without the other's delay. Much of what is loosely called concurrency is in fact sequential delay, where only one cause is truly on the critical path, so establishing genuine concurrency requires a careful criticality analysis of the programme.

Can a contractor claim an extension of time for concurrent delay?

In most FIDIC-based international practice, yes. Where an employer delay and a contractor delay are truly concurrent, the contractor is generally entitled to an extension of time for the period of concurrency, because an employer risk event caused critical delay to completion. The extension protects the contractor from liquidated damages for that period. However, this depends on the governing law and the specific contract terms, some of which allocate concurrency risk expressly, so the position should always be confirmed against the applicable contract and jurisdiction.

Can a contractor recover prolongation costs during concurrent delay?

Usually not for the period of genuine concurrency. The prevailing approach, reflected in the SCL Protocol, is that the contractor recovers an extension of time but not the time-related prolongation cost of a concurrent period, because it would have incurred those costs anyway due to its own concurrent delay. This is why time and money diverge in concurrency: the contractor keeps the time but not the money. The precise outcome varies by jurisdiction and contract wording, so the cost position should be assessed case by case.

Does concurrent delay mean the two delays cancel each other out?

No, and this is the most expensive misconception. Concurrency does not mean neither party has any entitlement. The contractor usually retains an entitlement to an extension of time for the concurrent period, which protects it from liquidated damages, even though it may not recover the associated prolongation cost. Assuming the delays simply cancel out leads contractors to stay silent, skip notices, and lose the time entitlement they actually held, exposing themselves to liquidated damages that a properly argued concurrency claim would have prevented.

What records do I need to prove concurrent delay?

You need a contemporaneously updated programme that shows the critical path and how it moves, so the criticality of each delay event can be demonstrated rather than reconstructed after the fact. You also need timely notices of every employer risk event, and cause-specific records that allow an analyst to separate the employer delay from the contractor delay over the relevant window. Because concurrency turns entirely on what was critical, when, and why, the strength of the argument is directly proportional to the quality of the programme and delay records kept at the time.

Concurrent delay does not forgive both sides equally. It usually gives you the time and withholds the money, and only if you claimed it. Silence is the one response that guarantees you lose both.

Note: This article provides general information on concurrent delay and is not legal advice. The treatment of concurrent delay differs between jurisdictions and depends on the governing law and the specific terms of the contract, including any express allocation of concurrency risk. Contractors should obtain advice tailored to the particular contract, project records, and applicable law before relying on any concurrency position.