Extension of Time Claim Letter: Template + How to Write It
It is Thursday afternoon, the Engineer's late drawing has stopped the slab pour, and someone on site says, "Just send a letter." Easy to say. Harder to do well at five o'clock with the clock already ticking. This guide gives you the template and walks through how to fill it in so the letter holds up later.
An Extension of Time claim letter is the first formal step in protecting the Contractor's right to more time. It is short, factual, and time-sensitive. Get it out fast and get it right, and the rest of the claim has a foundation to stand on.
This article is about the letter itself. If you want the wider picture of how Extension of Time works under FIDIC, the conceptual guide on Extension of Time covers entitlement, calculation, and delay analysis. Here we stay on the page in front of you.
1. What an Extension of Time Claim Letter Actually Is (and What It Isn't)
An Extension of Time claim letter is a written notice. It tells the Engineer that an event has occurred, that the event is delaying the Works, and that the Contractor intends to claim more time. That is all it has to do at this stage.
It is not the full claim. The detailed particulars, with the programme analysis and the number of days, come later. The letter opens the door; the particulars carry the argument through it.
People confuse the two and pay for it. A letter that tries to be the whole claim usually arrives late, because the Contractor waited to finish the delay analysis first. By then the notice clock has run out, and the best analysis in the world cannot rescue a notice that was never served on time.
Think of the letter as the smoke alarm and the particulars as the fire report. The alarm has one job: go off early. Nobody ever lost an Extension of Time because their notice letter was too short.
Key Takeaway: The claim letter is the initial notice, not the full claim. Its job is to flag the event and reserve the right to claim time. The detailed particulars and the day count come afterwards.
2. When the Clock Starts — and Why Late Letters Die
Under the FIDIC 1999 Red Book, the Contractor must give notice within 28 days of becoming aware, or of when it should have become aware, of the event or circumstance. That 28-day window is set by Clause 20.1. The 2017 Second Edition keeps the same 28-day period.
The trigger is awareness, not the date the delay finishes. This catches people out. The Contractor does not get to wait until the full effect of the delay is known before the clock starts; it starts when the Contractor first knew the event was happening.
Under the 1999 form, missing the 28 days can bar the time claim completely. There is no partial credit, no reduced entitlement, no second chance. The claim simply does not exist anymore, however strong the underlying facts were.
The 2017 Edition softened this a little by letting the Engineer consider whether the late notice caused any prejudice. It is a narrow lifeline, not a safety net. The honest advice is the same as it has always been: send the letter early. FIDIC has a way of humbling the contractor who decides the deadline is more of a guideline.
For a deeper look at the deadline mechanics, see the guide on the FIDIC 28-Day Rule.
Key Takeaway: The Clause 20.1 clock starts when the Contractor becomes aware of the event, not when the delay ends. Under the 1999 Red Book, missing the 28 days can bar the claim outright. Send early.
3. The Seven Things Every EOT Claim Letter Must Contain
A good notice letter is short, but it is not casual. Seven things should be on the page, and each one is there for a reason a tribunal would recognise.
- The recipient and the date. Addressed to the Engineer at the contractual address, with a clear date. The date is what proves the notice was on time.
- The contract reference. Project name, contract number, and the relevant Sub-Clause. This anchors the letter to the agreement.
- The event. What happened, in plain factual terms. One or two sentences. No argument yet.
- The date of awareness. When the Contractor became aware of the event. This is the date that starts the clock and shows the notice is within time.
- The effect on the Works. A brief statement that the event is delaying, or is likely to delay, completion. This links the event to the entitlement.
- The statement of intent to claim. A clear sentence that the Contractor gives notice of its intention to claim an Extension of Time, with a reservation of any associated cost.
- The commitment to particulars. A promise to submit detailed particulars within the contractual period, so the Engineer knows the full claim is coming.
Notice what is missing: no day count, no programme analysis, no legal argument. Those belong in the particulars. The letter that includes all seven items and nothing else is the one that does its job and gets out the door before the deadline.
Key Takeaway: Seven items make a complete notice letter: recipient and date, contract reference, the event, the date of awareness, the effect on the Works, the intent to claim, and the commitment to particulars. Leave the day count and the analysis for later.
4. Extension of Time Claim Letter — A Template You Can Adapt
Below is a template the Contractor can adapt. Replace each bracketed placeholder with the project facts. Keep the third-person voice and the formal tone; the letter is part of the contract record, not an email to a colleague.
- Heading block: To [Engineer's Name], [Engineer's Company], [Address]. From [Contractor's Name]. Date: [date of letter]. Reference: [Contract Number] – [Project Name].
- Subject line: Notice of Intention to Claim an Extension of Time pursuant to Sub-Clause [20.1] of the Conditions of Contract.
- Opening: The Contractor gives notice under Sub-Clause [20.1] of its intention to claim an Extension of Time to the Time for Completion in respect of the event described below.
- The event: On [date of event], [describe the event in plain factual terms, for example a late issue of construction drawings, an instructed Variation, or exceptionally adverse weather]. The Contractor became aware of this event and its effect on [date of awareness].
- The effect: The above event is delaying, or is likely to delay, the progress of the Works and the achievement of completion within the current Time for Completion. The affected activities include [briefly identify the affected work or section].
- The reservation: The Contractor reserves its right to claim any additional payment arising from this event, the particulars of which will follow with the detailed claim.
- The commitment: The Contractor will submit fully detailed particulars of this claim, including the supporting programme analysis and the period of Extension of Time claimed, within [42] days, or such other period as the Contract requires.
- Closing: This notice is given without prejudice to any other rights or entitlements of the Contractor under the Contract. Yours faithfully, [Name], [Position], for and on behalf of [Contractor's Name].
Two things to check before sending. First, confirm the particulars period against the actual contract; the 42-day figure is the FIDIC 1999 default, but a bespoke contract may set 14, 21, or 28 days. Second, make sure the Sub-Clause reference matches your edition. A wrong clause number in the subject line is the kind of small error that gives the other side something to argue about.
Key Takeaway: Use the template as a skeleton, then fill in the bracketed facts. Confirm two numbers against your own contract before sending: the Sub-Clause reference and the particulars period (42 days under FIDIC 1999, but bespoke contracts vary).
5. Worked Example: One Letter, Section by Section
Take a real situation. The Engineer issued revised reinforcement drawings 18 days late, which stopped the Contractor pouring a critical foundation. The Contractor noticed the impact the day the original pour was due. Here is how each section fills in.
Reference and subject. The heading carries the contract number and project name, and the subject line reads: Notice of Intention to Claim an Extension of Time pursuant to Sub-Clause 20.1. Anyone filing the letter knows in one line what it is.
The event. The Contractor writes that on 3 June 2026 the Engineer issued Revision C of the foundation reinforcement drawings, which the Contractor had requested for the pour scheduled on 16 May 2026. The Contractor became aware of the delaying effect on 16 May 2026, the day the pour could not proceed. That awareness date sets the deadline at 13 June 2026.
The effect. The letter states that the late drawings are delaying the foundation works, which sit on the critical path, and are likely to delay completion. It does not yet say by how many days. The Contractor does not have the programme analysis finished, and that is fine; the letter is not the place for it.
The reservation and the commitment. The Contractor reserves the right to claim associated cost and commits to submitting detailed particulars within 42 days. The letter goes out on 14 May 2026, well inside the 28-day window from awareness.
The whole letter is under a page. The detailed claim that follows might run to forty pages with a programme attached. But the one-page letter is what kept the claim alive, and that is the part people forget until the deadline has gone.
Key Takeaway: A worked example shows the letter stays factual and short. State the event, the date of awareness, and the effect on the critical path. The day count waits for the particulars; the one-page letter is what keeps the claim alive.
6. The Mistakes That Get EOT Letters Rejected
Most rejected notices fail for reasons that have nothing to do with the strength of the underlying delay. They fail on the basics.
- Sent late. The single most common killer. The event happened weeks ago and the letter only goes out once the delay is obvious to everyone, by which point the 28 days have passed.
- No date of awareness. Without it, the Engineer cannot tell whether the notice is in time, and the burden lands back on the Contractor to prove it was.
- Vague on the event. A letter that says progress has been affected generally, without naming the event, is not a notice of a claim. It is a complaint, and complaints do not start clocks.
- Wrong recipient or address. Sent to the site office instead of the contractual address, or to a person who is not the Engineer. The communications clause decides valid service.
- Trying to be the full claim. The Contractor delays the letter to include a day count and analysis, and misses the deadline doing it.
- Wrong clause reference. Citing the wrong edition's clause number, or no clause at all. Small, avoidable, and an open invitation to dispute the notice.
The pattern is clear. Letters die from being late, vague, or over-engineered, almost never from being too plain. When in doubt, send the simple letter on time. A tool like ChatNotice exists partly because so many sound claims were lost to a notice that was never sent or was sent a week too late.
Key Takeaway: EOT letters fail on procedure, not substance: sent late, no awareness date, vague on the event, wrong recipient, or over-stuffed with analysis the letter does not need. Simple and on time beats detailed and late every time.
7. After the Letter — Particulars, Records, and Follow-Up
Sending the letter is the start, not the finish. The Contractor's duty does not end with the notice; the detailed particulars still have to follow within the contractual period, 42 days under the FIDIC 1999 default.
The particulars are where the real work sits. This is the programme analysis, the calculated number of days, the contractual basis, and the evidence bundle. The conceptual Extension of Time guide covers how to build that analysis.
Between the letter and the particulars, records matter most. Daily reports, photographs, correspondence, and the contemporaneous programme are what turn a notice into a paid claim. Records gathered after the event always look like records gathered after the event, and the Engineer can tell.
Keep the file open. Update the Engineer if the effect of the delay grows, and serve a fresh notice for any new event rather than folding it into the old one. One notice per event keeps the record clean and the deadlines easy to track.
Key Takeaway: The letter is followed by detailed particulars within the contractual period (42 days under FIDIC 1999). Gather contemporaneous records as you go, and serve a separate notice for each new event rather than bundling them.
8. How the Letter Changes Across FIDIC, NEC4 and JCT
The same delay needs a different letter depending on the form of contract. The instinct to claim is the same; the procedure and the language are not.
Under FIDIC, the letter is a Notice under Clause 20.1, with the 28-day window from awareness and the detailed particulars to follow. The vocabulary is Engineer, Contractor, and Time for Completion. This is the form most of this guide is written for.
Under NEC4, the equivalent is a Compensation Event notification, and the rules are tighter and faster. The Contractor notifies within eight weeks of becoming aware, and the assessment is forward-looking, built on a quotation rather than a retrospective claim. NEC4 also rewards early warning, and failing to give one can reduce the assessment.
Under JCT, the Contractor gives notice of a Relevant Event to the Architect or Contract Administrator as soon as it becomes reasonably apparent. There is no single fixed day count like FIDIC's 28 days; the test is reasonable promptness, which sounds gentler but is easier to argue about later.
The practical lesson is to read the contract in front of you before you reach for a template. A FIDIC letter sent on an NEC4 job is a Compensation Event notified under the wrong name, and the form of contract has no sense of humour about that.
Key Takeaway: FIDIC uses a Clause 20.1 Notice within 28 days of awareness. NEC4 uses a Compensation Event notification within eight weeks, built on a forward quotation. JCT uses a Relevant Event notice as soon as reasonably apparent. Match the letter to the contract you are actually under.
Frequently Asked Questions
Is an EOT claim measured in calendar or working days?
Under the FIDIC 1999 Red Book and the 2017 Second Edition, the Time for Completion is expressed in days, which means calendar days unless the Particular Conditions say otherwise. An Extension of Time therefore adds calendar days to the completion date, including weekends and public holidays. Always check the Particular Conditions, because a bespoke contract can redefine a day as a working day. When the Contractor states the number of days claimed, it should match the unit the contract uses.
Is the claim letter the same as the full claim or particulars?
No. The claim letter is the initial notice that tells the Engineer an event has occurred and the Contractor intends to claim. The full claim, the detailed particulars, comes later and contains the programme analysis, the calculated number of days, and the supporting evidence. Under FIDIC the notice comes within 28 days of awareness and the fully detailed claim follows within 42 days. Sending the letter does not discharge the duty to submit particulars.
What if I already missed the 28-day deadline?
Send the letter immediately rather than waiting longer, because every extra day weakens the position. Under the FIDIC 1999 Red Book, missing the 28-day notice can bar the time claim entirely. The 2017 Second Edition allows the Engineer to consider whether the late notice caused any prejudice, which gives a narrow route to argue the claim should still stand. Either way, serve the notice, record the reason for delay, and take advice on the specific contract.
Do I need a Claims Consultant to write it?
Not for the initial notice letter. The letter is a short, factual document any competent Project Manager or Contracts Engineer can write, and a Claims Consultant is rarely needed at this stage. The detailed particulars that follow, especially the delay analysis on a complex project, are where specialist help often earns its fee. Get the letter out on time first, then decide whether the particulars need expert support.
Can the letter be sent by email or must it be a formal letter?
Check the contract's communications clause, because that decides what counts as valid service. The FIDIC 1999 Red Book requires notices in writing delivered to the agreed address, and many contracts now accept email if the address and method are set out in the Particular Conditions. The safe approach is to send a formal letter to the named recipient and copy it by email, so the form of the document is never the reason the claim fails.