---
title: NEC4 Engineering and Construction Subcontract (ECS) High Level User Guide
date: 2025-03-17T08:18:53Z
modified: 2025-09-29T16:55:15Z
permalink: "https://gmhplanning.co.uk/nec-downloads/nec4-engineering-and-construction-subcontract-ecs-high-level-user-guide/"
type: downloads
status: publish
excerpt: ""
wpid: 7834
nec_contract_type:
  - NEC4
nec_contract_version:
  - NEC Engineering & Construction Subcontract (ECS)
download_category:
  - Contract types & documentation
featured_image: "https://gmhplanning.co.uk/wp-content/uploads/2025/03/NEC4-Engineering-and-Construction-Subcontract-ECS-e1742319644183.jpg"
featured_image_alt: NEC4 Engineering and Construction Subcontract (ECS)
author: Glenn Hide
timestamp: 2025-09-29T16:55:15Z
tags:
  - NEC4
  - NEC Engineering & Construction Subcontract (ECS)
  - Contract types & documentation
---

## Introduction

This NEC4 Engineering and Construction Subcontract (ECS) high-level overview is intended to be a quick reference guide as to where a particular subject matter can be found within the contract. This guide focuses on the most commonly used and relevant day to day clauses likely to be most relevant. For a specific project, any bespoke clause amendments introduced by a Contractor would have to be taken into account. Sections 1-8 are the core clauses for every ECS option A-E contract, followed by option specific clause details.

## NEC4 ECS Section 1 – General 

### Actions

**10.1** Reminder that all Parties are to act as stated in the contract.

**10.2** Obligation to also act in a spirit of mutual trust and cooperation.

### Defined Terms

**11.2** In alphabetical order.

### Communications

**13.1** All communications in a form that can be read, copied and recorded.

**13.2** Communications are only valid if submitted by the system stated in Scope.

**13.3** Responses within period for reply or as stated in contract.

**13.5** Contractor may extend period for reply by agreement.

**13.7** Any notification has to be separate from any other communication.

### Contractor 

**14.1** Contractor acceptance does not transfer liability from Subcontractor.

**14.2** Contractor must formally delegate actions in writing.

**14.3** Contractor can issue instructions to change the Scope.

### Early Warnings

**15.1** Reasons for which an early warning should be notified.

**15.2** Either party can instruct the other to an early warning meeting.

**15.3** Actions expected of all parties at an early warning meeting.

**15.4** Updating of the Early Warning Register by the Contractor.

### Subcontractor’s Proposals

**16.1** Subcontractor can propose value engineering to reduce Prices.

**16.2** Contractor responds to value engineering proposal within 5 weeks.

**16.3** Subcontractor may propose a change to Working Areas.

### Ambiguities

**17.1** Notifying and resolving of an ambiguity between contract documents.

**17.2** Notifying and resolving of an illegal or impossible requirement.

## NEC4 ECS Section 2 – Subcontractors Responsibilities

### Providing the Works 

**20.1** Subcontractor obligation to Provide the Works in accordance with Scope.

### Design

**21.1** Subcontractor design responsibility as stated in Scope.

**21.2** Subcontractor to submit design and Contractor to accept/not accept.

**21.3** Design submission can be submitted in parts if suitable.

### People 

**24.1** Subcontractor to provide a key person stated in CD2 or equal replacement.

**24.2** Contractor can instruct Subcontractor to remove any person.

### Working with Contractor and Others

**25.1** Requirement for Subcontractor to work with Others as instructed/in Scope.

**25.3** Liable costs if Subcontractor fails to achieve Key Date in CD1.

### Subsubcontracting

**26.2** Requirement to submit proposed Subsubcontractor for acceptance.

**26.2** Reasons under which a Subsubcontractor can be **not** accepted.

**26.3** Also have to submit contract terms for Subsubcontractor for acceptance.

### Other responsibilities

**27.3** Subcontractor obeys written instructions given by Contractor.

**27.4** Subcontractor acts in accordance with Health & Safety as stated in Scope.

### Disclosure

**29.2** Subcontractor may only publicise works with Contractor’s agreement.

## NEC4 ECS Section 3 – Programme

### Date / Completion Date 

**30.1** Subcontractor does not start work on site until the first access date.

**30.2** Contractor certifies date of Completion within 1 week of that date.

### The Programme

**31.1** Requirement for Subcontractor to submit first programme for acceptance.

**31.2** Detailed list of what is required to be shown on programme for acceptance.

**31.3** reasons for Contractor not to accept an programme.

### Revising the Programme

**32.1** List of what should be shown on a Subcontractor’s revised programme.

**32.2** Intervals for programme submissions to Contractor.

### Acceleration

**36.1** Either party can propose acceleration which is then instructed.

**36.2** Subcontractor issues acceleration quote for acceptance.

## NEC4 ECS Section 4 – Quality Management

### Quality Management System

**40.1** Subcontractor operates a quality management system in line with Scope.

**40.2** Quality policy statement and plan issued for Contractor acceptance.

### Tests and Inspections

**41.1** Requirement to carry out tests and inspections as per Scope/applicable law.

**41.3** Requirement to notify Contractor prior to tests being carried out.

**41.5** Requirement for Contractor to carry out tests/inspections.

**42.1** Requirement to carry out tests prior to delivery where required.

### Searching/Notifying Defects

**43.1** Contractor can instruct Subcontractor to search for a defect.

**43.2** Requirement Contractor/Subcontractor to make each other aware of defects.

### Correcting Defects

**44.2** Requirement to correct a defect within the defect correction period.

**44.3** Contractor to issue defects certificate at end of defects date.

### Accepting Defects

**45.1** Can propose for defect to not be corrected and Scope changed accordingly.

**45.2** Subcontractor to submit resultant quotation saving for accept/not accept.

**46.1** Contractor can assess costs of uncorrected defects and charge Subcontractor.

## NEC4 ECS Section 5 – Payment

### Assessing the Amount Due

**50.1** Contractor to assess the amount due at each assessment date.

**50.2** Definition of the amount due for each application.

**50.4** If Subcontractor not submit application on time will be assessed as zero.

**50.5** 25% PWDD can be withheld if no 1st accepted programme.

### Payment

**51.1** Contractor to certify payment within 2 weeks of assessment date.

**51.2** Confirmation of period within which payment should be made.

**51.3** Interest recoverable on items corrected on a later certificate.

**51.4** Interest recoverable on late payments.

### Defined Cost

**52.1** Any Subcontractor’s costs not identified in Defined Cost are in the Fee.

**53** Final Assessment – section on how/when final assessment is made at end.

## NEC4 ECS Section 6 – Compensation Events

### Compensation Events

**60.1** List of what events would be valid compensation events (21 reasons).

**60.2** Ambiguity in Site Information favours Subcontractor.

### Notification

**61.1** Contractor notifies compensation event at time of issuing instruction.

**61.2** Contractor instructs Subcontractor to produce quotation (and proceed).

**61.3** Subcontractor can notify a CE and can be time barred after a period if late.

**61.4** Contractor to accept or not accept if Subcontractor has notified a CE.

**61.4** Deemed acceptance if the Contractor does not respond to reminder.

**61.5** Contractor can advise that an early warning could have been given.

**61.6** Contractor can state assumptions for Subcontractor to base the quote upon.

**61.7** No compensation events can be issued after Completion.

### Quotations

**62.1** Contractor can request alternative quotations for dealing with a CE.

**62.2** Subcontractor to provide a quote and alterations to programme (if relevant).

**62.3** Subcontractor to provide quote within 2 weeks, C response within 4 weeks.

**62.4** Contractor can instruct a revised quote (after explaining why).

**62.5** Contractor can extend period for Subcontractor to produce quote.

**62.6** Subcontractor’s quote deemed accepted if no response to reminder.

### Assessment

**63.1** Basis of quotes in relation to if should be actual or forecast defined cost.

**63.4** Only reasons stated for which Prices can be reduced.

**63.5** Definition of reasons for contractual movement in Completion Date.

**63.7** Contractor may assess as though early warning had been given if it wasn’t.

**63.8** Rules for allocation of risk within a compensation event quotation.

**63.9** Requires Subcontractor to act promptly and competently to a CE.

**63.10** How ambiguities will be assessed in terms of a compensation event.

### Contractor’s Assessments

**64.1** Reasons under which Contractor can make own assessment of a CE.

**64.3** Contractor to notify Subcontractor of their own assessment of a CE.

**64.4** Deemed acceptance if Contractor no response to a notification reminder.

### Proposed Instructions

**65.1** Contractor can instruct a quotation for proposed instruction.

**65.2** Subcontractor submits quotation within 2 weeks and Contractor to respond.

**65.3** If quotation not accepted Contractor can still instruct (and assess as CE).

### Implementation

**66.1** Implemented when CE accepted/assessed/deemed accepted.

**66.2** Prices/Completion Date changed accordingly following agreement.

**66.3** Compensation event quote is not changed if later found to be wrong.

## NEC4 ECS Section 7 – Title

**70.1/2** Title of materials transfers from Subcontractor to Contractor.

**71.1** Contractor marks Equipment, Plant and Materials outside Working Area.

**73.1** Subcontractor has no title to anything found/existing on the site.

**73.2** Subcontractor has title to materials from excavation and demolition.

## NEC4 ECS Section 8 – Risks and Insurance

**80.1** List of Contractor’s liabilities.

**81.1** List of Subcontractor’s liabilities.

**83**  Insurance cover details.

**84/5** Insurance policies and who needs to provide what to whom.

## NEC4 ECS Section 9 – Termination

**91.1** List of valid reasons for termination.

**92**  Procedures to follow upon termination.

## NEC4 ECS Additional Option A clauses

**11.2** Option A specific identified and defined terms.

**31.4** Requirement for activity schedule to relate to items on programme.

**31.4** Requirement for activity schedule to relate to items on programme.

**55.1** Clarifies that Activity Schedule is not Scope.

**55.3** Subcontractor may submit revised Activity schedule for acceptance.

**55.4** Reasons Contractor has for not accepting a revised Activity Schedule.

**63.12** Adjustment of Prices in line with value engineering percentage.

**63.16** Ascertaining a new People Rate where required.

## NEC4 ECS Additional Option B clauses

**11.2** Option B specific identified and defined terms.

**56.1** Clarifies that Bill of Quantities is not Scope.

**60.4** Threshold at which a change in quantity is assessed as a CE.

**60.5**  If any change in quantity affects Completion, then it is a CE.

**60.6** Reasons to correct a mistake in B of Q which will be a compensation event.

**60.6** Reasons to correct a mistake in B of Q which will be a compensation event.

**60.7** Hierarchy between B of Q and other documents (B of Q takes precedence)**.**

**63.12** Adjustment of Prices in line with value engineering percentage.

**63.15** Adjustment of Bill of Quantities for compensation events.

**63.16** Ascertaining a new People Rate where required.

## NEC4 ECS Additional Option C clauses

**11.2** Option C specific identified and defined terms.

**20.3** Subcontractor provides forecast of total Defined cost at contract intervals.

**26.4**  Subcontractor to submit pricing information for each Subsubcontractor.

**41.7** Liability of costs for carrying out repeat test or inspection.

**50.7** Payments in other currencies.

**52.2** Opportunity for finalising Defined Costs for part of the works.

**54.2** Requirement for Subcontractor to keep records.

**54.1/2** C assesses Subcontractor’s share of the Prices and actual defined cost.

**54.3** Provisional assessment of Subcontractor’s share following Completion.

**54.4** Final assessment of Subcontractor’s share following Completion.

**55.2** Clarifies that information in Activity Schedule is not Scope.

**63.13** Prices are not reduced if was a Subcontractor idea to reduce defined cost.

**93.4**  Rules on assessing share in event of termination of the contract.

## NEC4 ECS Additional option D clauses

**11.2** Option D specific identified and defined terms.

**20.3** Subcontractor provides forecast of total Defined cost at contract intervals.

**26.4** Subcontractor to submit pricing information for each Subsubcontractor.

**41.7** Liability of costs for carrying out repeat test or inspection.

**50.7** Payments in other currencies.

**50.9** Opportunity for finalising Defined Costs for part of the works.

**52.2** Requirement for Subcontractor to keep records.

**54.5/6** C assesses Subcontractors share of the Prices and actual defined cost.

**54.7** Provisional assessment of Subcontractor’s share following Completion.

**54.8** Final assessment of Subcontractor’s share following Completion.

**56.1** Clarifies that information in Bill of Quantities is not Scope.

**60.4** Threshold at which a change in quantity is assessed as a CE.

**60.5** If any change in quantity affects Completion, then it is a CE.

**60.6** Reasons to correct a mistake in B of Q which will be a compensation event.

**60.7** Hierarchy between B of Q and other documents (B of Q takes precedence).

**63.13** Prices are not reduced if was a Subcontractor idea to reduce defined cost.

**63.15** Changes to Bill of Quantities for compensation events.

**93.5** Rules on assessing share in event of termination of the contract.

## NEC4 ECS Additional Option E clauses

**11.2** Option E specific identified and defined terms.

**20.3** Subcontractor provides forecast of total Defined cost at contract intervals.

**26.4** Subcontractor to submit pricing information for each Subsubcontractor.

**41.7** Liability of costs for carrying out repeat test or inspection.

**50.8** Payments in other currencies.

**50.9** Opportunity for finalising Defined Costs for part of the works.

**52.2** Requirement for Subcontractor to keep records.

## NEC4 ECS Secondary Options 

### X1 Price Adjustment for Inflation

**X1.1** Defined terms – Base Date Index, Latest Index, Price Adjustment Factor.

**X1.2** How Price Adjustment Factor is applied

**X1.3/4** Price adjustment for amount due.

**X1.5** Defined cost for compensation events.

### X2 Changes in law

**X2.1** CE if occurs after the Contract Date.

### X3 Multiple Currencies

**X3.1/2** Payment and exchange rates.

### X4 Ultimate Company Guarantee

**X4.1/2** Given within 4 weeks of Contract Date.

### X5 Sectional Completion

**X5.1** Completion/Completion Date apply to sectional.

### X6 Bonus for Early Completion

**X6.1** Paid per day at rate in CD1.

### X7 Delay Damages

**X7.1** Charged at rate stated in CD1 until Completion or take over.

**X7.2** Contractor repays overpayment of damages with interest.

**X7.3** Delay damages are reduced with partial take over.

### X8 Undertaking to Client or Others

**X8.1-5** As stated in CD1.

### X9 Transfer of Rights

**X9.1** Contractor owns Subcontractor’s rights over materials.

### X10 Information Modelling

**X10.1** Defined terms.

**X10.2**  Subcontractor collaborates with other Information Providers.

**X10.3** Early warning requirement for anything could impact Information Model.

**X10.4** Submission of Information Execution Plan.

**X10.6** Compensation events.

**X10.7** Client, Contractor and Subcontractor liabilities.

**X11.2** X11Termination by Contractor – procedures and amount due to be paid.

### X12 Multiparty Collaboration

**X12.1** Identified and defined terms.

**X12.2** Actions to be taken by Partners and Core Group.

**X12.3** Collaboration by all Parties.

**X12.4** Incentives – amounts paid to Partner if KPI(s) achieved.

### X13 Performance Bond

**X13.1** Required as stated in CD1.

### X14 Advanced Payment to Subcontractor

**X14.1** Advanced payment made as stated in CD1 at the first assessment date.

**X14.2** Potential for advanced payment bond that may be required.

**X14.3** Advanced payment repaid to Contractor in instalments as stated in CD1.

### X15 Subcontractor’s Design

**X15.1-5** Liabilities and ownership of materials.

### X16 Retention

**X16.1** Amounts retained in amounts due until Completion/take over.

**X16.2** Amount retained is halved in the next assessment after Completion.

**X16.3** Potential for an alternative retention bond if agreed by Contractor.

### X17 Low Performance Damages

**X17.1** For defects that miss performance levels.

### X18 Limitation of Liability

**X18.1-4** Limits of liability as stated in Contract Data part 1.

**X18.5** Excluded matters that remain unlimited liability.

**X18.6** Subcontractor only liable for matters notified before end of liability period.

### X20 Key Performance indicators and Reporting Requirements

**X20.1-5** As per CD1.

### X21 Whole Life Cost

**X21.1** Subcontractor can propose Scope change to reduce life cost of an asset.

**X21.2** Subcontractor to submit quotation if C prepared to consider change.

**X21.3** Contractor responds to quotation within period for reply.

**X21.5** Contractor changes Scope/Prices/Completion Date accordingly.

### Schedule of Cost Components (for use with options C/D/E)

**11-14** Payments applicable for people.

**21-28** Payments applicable for Equipment.

**31/32** Payments applicable for Plant and Materials.

**41** Payments applicable for Subsubcontractors.

**51-54** Cost of charges paid or received by the Subcontractor.

**61** Cost of manufacture of Plant and Materials by Subcontractor.

**71/72** Subcontractor cost of design of works/Equipment outside Working Areas.

**8**  Insurance premiums and insurable events excluded from cost.

### Short Schedule of Cost Components (for use with options A/B)

**11** Payments applicable for people

**21-27** Payments applicable for Equipment.

**31/32** Payments applicable for Plant and Materials.

**41**  Payments applicable for Subsubcontractors.

**51-54** Cost of charges paid or received by the Subcontractor.

**61**  Cost of manufacture of Plant and Materials by Subcontractor.

**71/72** Subcontractor cost of design of works/Equipment outside Working Areas.

**8** Insurance premiums and insurable events excluded from cost.

## Abbreviations:

**CD1** Contract Data part 1

**CD2** Contract Data part 2

**C**  Contractor

**CE** Compensation event

**B of Q** Bill of Quantities

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