Deemed Acceptance Under NEC: How Silence Accepts a Compensation Event

By Sheldon Wright MCICES. Last reviewed September 2026. Covers NEC3 and NEC4 ECC.

Everyone working on an NEC project has heard about the eight-week time bar, because a Contractor or Subcontractor who misses it can lose entitlement to a compensation event. However, fewer people pay the same attention to the mechanism that threatens the other side. Under NEC, a Project Manager who does not respond in time can be treated as having accepted that a notified event is a compensation event, or as having accepted the Contractor's quotation at its full value, without anyone having assessed it.

The contract's phrase is "treated as" accepted, and the industry calls it deemed acceptance. It was written in deliberately, and once it operates it is very hard to undo. If you assess compensation events for a living, it is the largest process risk you carry. If you submit them, it is a right you hold and probably do not use.

This article explains the three places it appears, the exact sequence that triggers it, and how each side should manage it. I paraphrase the contract throughout, so read your own clauses, and check whether a Z-clause has altered or deleted them.

In twenty years, I have never had a quotation accepted by default. However, I have come close on a number of occasions. What I have done, more than once, is send a general communication setting out that the period had run out and what followed from that. The reply has arrived shortly afterwards every time.

Note what that is and is not. A notification of failure under clause 61.4, 62.6 or 64.4 is a formal step that starts a second period running. A general communication pointing out that the first period has expired is not that step: it is a warning that you are about to take it. In my experience the warning has always been enough, which is why I have never needed the step itself.

That is worth saying plainly, because it is the most useful thing I know about these clauses. Their value is not the outcome. It is that they give you something to point at, and a Project Manager who is shown the clause and the date will usually deal with the event that week.

The provisions sit unused not because they are controversial but because the contract management systems used across the industry generally do not track these dates, so the periods go unmonitored — I suspect because the clauses are awkward to model, with a notification of failure starting a second period inside the first.

Why the contract works this way

NEC is built on the idea that change should be dealt with when it happens. That only works if both parties act within their periods. The Contractor's discipline is enforced by the time bar. If the Project Manager faced no equivalent, a Contractor could notify on time and quote on time, and then wait months for an answer while funding the work. The treated-acceptance provisions are the contract's way of making the Project Manager's deadlines mean something.

There is a sharper reason than symmetry, and it explains why these clauses arrived when they did. Under NEC2 the assessment was meant to be built on the Contractor's quotation, but nothing in the contract stopped a Project Manager undermining that simply by doing nothing. It was even argued, circularly, that a quotation which had not been instructed had no status at all, and that the Contractor had no right to submit one — only a duty to do so when told. The three provisions below were written to close that off.

So they are not a trap for the slow Project Manager. They are what makes the Contractor's quotation the starting point in the first place.

They have been part of the form since NEC3 was published in 2005, and NEC4 kept them with minor refinements. Project teams are still surprised by them.

The three mechanisms

The pattern is the same each time. The Project Manager misses a period. Nothing happens automatically at that point. The Contractor may then notify the Project Manager of the failure. If the failure continues for a further two weeks after that notification, the contract treats the Project Manager as having accepted.

1. Silence on a notification: clause 61.4

When the Contractor notifies a compensation event under clause 61.3, the Project Manager has one week to reply, or a longer period if the Contractor agrees. The reply either explains that the Prices and dates will not change, for one of the reasons the clause lists, or confirms the compensation event and instructs a quotation.

If the Project Manager does not reply in time, the Contractor may notify that failure. If the Project Manager still has not replied two weeks after that, the silence is treated as acceptance that the event is a compensation event and as an instruction to submit a quotation.

Entitlement is conceded at that point. The Project Manager can no longer argue that the event was the Contractor's fault or was not one of the listed events. The argument that remains is about the amount.

2. Silence on a quotation: clause 62.6

The Project Manager has two weeks to reply to a quotation. The permitted replies are to accept it, to instruct a revised quotation and explain why, or to notify that the Project Manager will make their own assessment.

If the Project Manager does not reply within the time allowed, the Contractor may notify the failure. Where more than one quotation was submitted for the event, the notification says which one the Contractor proposes should be treated as accepted. If the failure continues for two more weeks, that quotation is treated as accepted. Quotations for proposed instructions are outside the mechanism. NEC3's clause 62.6 says so expressly. NEC4 deals with proposed instructions in its own clause 65, under which a quotation that receives no reply by the stated date is simply not accepted.

This is the mechanism with the largest financial consequence. The quotation is accepted as submitted, including its cost, its delay, its risk allowances and its errors.

3. Silence on the Project Manager's own assessment: clause 64.4

Where the Project Manager has decided to make their own assessment, they must notify it within the same period the Contractor was allowed for the quotation, which is three weeks under the standard form. If they do not, the Contractor may notify the failure, and if it continues for a further two weeks, the Contractor's quotation is treated as accepted.

This catches Project Managers who reject a quotation, quite reasonably, by saying they will assess it themselves, and then never find the time. Telling the Contractor "I will do my own assessment" does not protect the Project Manager unless the assessment follows within the period. Note also what kind of reply stops the final two weeks. The clause does not say, but a reply promising an assessment in due course would defeat its purpose. I would assume that only the assessment itself will do.

What stops the clock, and what does not

A Project Manager who cannot reply in time has one clean route and two that get misused.

Agree an extension before the deadline (clause 62.5). Both the period for the Contractor to submit a quotation and the period for the Project Manager to reply can be extended, but only if the two of them agree to it before the submission or reply is due, and the Project Manager then confirms the extension. Note the order. An extension agreed after the period has run does not revive it, and a Project Manager who realises on the Friday that Monday's deadline has passed has nothing left to extend. Ask while you still have time to give away.

Instruct a revised quotation (clause 62.4), with your reasons. This starts a fresh three weeks, and the clause allows it only after the Project Manager has explained why. Some reasons are sound: assumptions may have been stated late, so the quotation was built on the wrong basis. Others are weaker. Substituting the Project Manager's own assumptions without going through the assumptions route, or simply swapping the Contractor's risk allowances for the Project Manager's, is using the clause as a delaying device rather than for its purpose. A Contractor receiving one is entitled to ask which reason applies.

Make your own assessment (clause 64.1) — but the power is not general. This is the one reached for most often and examined least. Clause 64.1 lists the situations in which the Project Manager assesses the event, and that list is the whole of the power. There is no free-standing right to set a quotation aside because the Project Manager would have priced it differently. The rest of the contract points the same way: once an event is implemented the assessment stands even if the forecast behind it turns out to have been wrong (NEC3 clause 65.2; NEC4 clause 66.3 puts it more broadly still). The Contractor carries the risk of its own forecast — and that bargain only makes sense if the Contractor's quotation is genuinely the basis of the assessment, rather than an opening bid the Project Manager can discard.

And what happens in practice. None of that stops it happening. On projects run through contract management software, the Project Manager implements the event under their own assessment without giving notice first — a figure entered, a status changed, and the event is implemented at the Project Manager's number. It happens regularly, and the system shows a properly implemented event afterwards, because the system does not record which route was taken.

Two things have gone wrong there, and it is worth separating them. The first is the gateway: if none of the situations in clause 64.1 applied, there was no power to assess at all. The second is the notice. A reply to a quotation has to be one of the replies the contract lists, one of which is notifying that the Project Manager will be making their own assessment (clause 62.3), and the assessment itself is then notified with details (clause 64.3). More to the point, an event is implemented on the Project Manager's own assessment when the Project Manager notifies it — NEC3 clause 65.1, NEC4 clause 66.1. If no notification was given, nothing was implemented, whatever the status field says.

That argument is cleaner on paper than it is in the middle of a job, because by then the Prices have moved, the certificate has followed and the software will not let anyone edit a closed event. Unpicking it inside a rigid system is the real difficulty, and it is usually harder than the contractual position.

The way through is normally a second event, not a fight about the first. Agree a further compensation event that uplifts the implemented one to the right figure. There is no clause that provides for this — it is an agreement between the parties, and it should be recorded as one — but it gets the money right without an adjudication, it works inside the software, and it is what commercial teams on both sides usually want. It leaves two entries on the register where there should be one, so say in the second what it corrects.

For the Contractor, the thing that makes that conversation easy is a contemporaneous letter. If an assessment appears without notice, write at the time: the event has been implemented without the notification the contract requires, you do not accept the assessment, and you will be looking to correct it. Sent that week, it makes the uplift a correction. Raised six months later, it is a renegotiation, and it will be treated as one.

Why it is so hard to undo

A quotation that is treated as accepted is implemented under the contract in the same way as one the Project Manager accepted deliberately (clause 66 in NEC4, clause 65 in NEC3). The Prices and the Completion Date change. The contract then provides that an implemented assessment is not revised if its forecasts later prove wrong.

After that, the route to reopening it is the dispute procedure. The contract does leave that door open. In NEC3, Options W1 and W2 include, among the adjudicator's powers, the power to alter a quotation that has been treated as accepted. NEC4 widens the wording to any matter that has been treated as accepted or correct. Under Option W1 the Employer, or the Client in NEC4, may refer a dispute about a treated acceptance, and has four weeks from the date it was treated as accepted to raise it. So a treated acceptance is not beyond challenge in the way that some people assume.

That is small comfort. The Client has to start an adjudication, pay for it, and persuade an adjudicator to reduce a quotation that the contract has already implemented. The Prices have changed in the meantime, and the money may have been paid. Commercially, the Client is arguing from a weak position, and doing so because someone missed a date.

The arithmetic that catches people

The sequence for a quotation runs like this.

If the Contractor sends the reminder promptly, a quotation can be accepted by default four weeks after it was submitted. On a project with fifty or sixty quotations in progress and a small commercial team, four weeks passes quickly. August and Christmas make it worse.

Note also that the reminder is a trigger, not a courtesy. The two weeks run from the Contractor's notification of the failure. A Project Manager who receives one should stop what they are doing and deal with it.

If you are the Project Manager or the Client's commercial team

Run the register by reply dates. Every open notification and quotation needs a reply-due date, and the register should be sorted by it. Value tells you which events matter commercially. The date tells you which ones can hurt you this week.

Triage on day one. On arrival, give every quotation a quick first read to see whether it is complete enough to assess: whether there is a build-up, whether there is a programme where delay is claimed, and whether the arithmetic holds. If it is not, the correct response is an instruction to submit a revised quotation, with reasons, and it can go out well inside the two weeks. That is a valid reply, and it stops the clock properly. The checks themselves are the same every time, which is what makes them a drain on the week and also what makes them automatable: Clause 60 runs that first pass for you, with every finding cited to the document it came from, so the hours you have go on the two or three events that genuinely need a quantity surveyor's judgement rather than on working out which ones those are. You still make the assessment.

Do not rely on holding replies. "We are reviewing your quotation and will respond shortly" is not one of the replies the contract lists. I would not want to defend it as a reply under clause 62.3.

Agree extensions properly. The contract allows the periods to be extended, but only by agreement between the Project Manager and the Contractor, reached before the reply falls due. An extension you awarded yourself, or one agreed after the date passed, does not protect you. Get the agreement in writing through the contract's communication system.

Treat a failure notice as urgent. Whoever receives contractual communications needs to recognise a notification of failure to reply on sight and escalate it the same day.

If you choose to assess it yourself, notify first and put the deadline in the diary. The contract wants the reply telling the Contractor you will be assessing it, and then the assessment itself, notified with details, inside the period. Clause 64.4 exists for Project Managers who take this route and then let the period run out. And because a system will usually let you enter an assessment straight onto an event, it is worth saying: implementing one without the notification is not a shortcut. It leaves the Contractor with a good argument that nothing was implemented at all, and it is normally unwound by agreeing a second event to uplift the first — two entries on the register, and a conversation you did not need to have.

Know what your Z-clauses say. Many Clients delete or soften these provisions. Many do not. Find out at the start which contract you are administering.

If you are the Contractor

You have to act. Nothing is treated as accepted unless you notify the failure. No reminder means no deemed acceptance, however long the silence lasts.

Somebody has to be counting. This is the practical barrier, not nerve. If your register records when a quotation was submitted but not when the reply was due, the moment passes unremarked. Put the reply-by date on the register next to the submission date, and look at it weekly. Our free change management register calculates both, along with the treated-acceptance dates that follow a notification of failure, because that arithmetic is exactly what gets dropped.

The quotation has to be one you can stand behind. A quotation accepted by default will be examined very hard afterwards by people looking for a way out. If it contains errors, double-counting or unsupported delay, you will be defending it in adjudication and in the relationship. The right only has value when the quotation is sound.

Send the notice formally. It is a notification under the contract, so send it separately from other communications, through the contract's system, with the clause identified. A friendly reminder in an email about something else does not start the two weeks.

Think about the relationship, but not for too long. Many contractors never use these clauses because they do not want to be seen as aggressive. I understand that. My view is that a polite, factual notification of failure to reply is the contract working as intended, and that most Project Managers respect it. The alternative is funding the Client's change for months, and that is an expensive way to be liked.

The point for directors

On the Client side, deemed acceptance is a governance risk that rarely appears on a risk register. A quotation accepted by default is expenditure that nobody assessed. On a framework or a programme with several Project Managers, the exposure depends on how disciplined the least organised team is during its busiest month. The control is unglamorous: a register run by date, enough assessment capacity to reply inside the period, and visibility of overdue replies above project level.

On the Contractor side, quotations that sit unanswered are cash you are funding. The contract gives your teams a lever, and it is worth asking whether they know it exists.

Where Clause 60 fits

Deemed acceptance is a capacity problem at root. Project Managers miss reply periods because a proper first-pass assessment takes hours and the quotations arrive faster than the hours do. Clause 60 reads the quotation and cost build-up, the contract including Z-clauses, and the native Primavera P6 programme, and returns a structured first-pass review in about ten minutes, with several events able to run at once. Each section is RAG-rated, every finding is cited to its source and labelled Fact or Inference, and gaps are flagged. It gives the assessor a worked-through starting point on day one. That is usually enough to decide whether the right reply is to accept, to instruct a revision or to assess it yourself, and to send that reply inside the period.

It is assistive, not advisory. The Project Manager still makes the assessment and signs it.

You can see a complete review of a sample NEC4 event at clause60.com/demo, with no sign-up needed.

This article is general guidance on the standard NEC3 and NEC4 ECC forms, written from professional experience. It is not legal advice. The effect of these provisions depends on the exact words of your contract, including any Z-clause amendments, and on the facts. NEC is a registered trade mark of its owner; Clause 60 Limited is not affiliated with or endorsed by NEC.