NEC Core Clauses Explained

The NEC core clauses are the rules that apply to every Engineering and Construction Contract, whichever main Option you choose. They're split into nine sections, from general terms through to termination, and the main and secondary Options add to them. Learn what each section does, and you'll know where to look for almost any question on site.

This guide follows the NEC4 ECC. The Engineering and Construction Subcontract uses the same numbering, with changes for its different parties, and other forms vary. It's an explanation of what each section covers, not the contract's wording, so read your own copy, including amendments. It forms part of how an NEC contract is structured and the wider comparisons section.

The nine sections at a glance

Section	Heading	Questions it answers
1 (10-19)	General	How do we communicate? Who can instruct? What do the terms mean?
2 (20-29)	The Contractor's main responsibilities	What must the Contractor provide, design and manage?
3 (30-36)	Time	When does it start and finish? What goes in the programme?
4 (40-46)	Quality management	Who tests? What happens with Defects?
5 (50-53)	Payment	How much is due, and when?
6 (60-66)	Compensation events	What can change the Prices and dates? How's it assessed?
7 (70-73)	Title	Who owns Plant and Materials? What about objects found on Site?
8 (80-86)	Liabilities and insurance	Who carries which risks? What's insured?
9 (90-93)	Termination	How can the contract be ended, and what's paid?

What each section does

Section 1: General

This sets the ground rules. Clause 10 has the obligation to act as the contract says, with mutual trust and co-operation. Clause 11 covers defined terms, and clause 12 deals with interpretation and the law. Clause 13 controls communications. Clause 14 deals with the Project Manager and Supervisor. Clause 15 covers early warnings. Clause 16 lets the Contractor propose a change to the Scope that would reduce what the Client pays, 17 covers instructions and ambiguities, 18 corrupt acts and 19 prevention.

Section 2: The Contractor's main responsibilities

Clause 20 is the core duty to provide the works in line with the Scope. Clauses 21 to 23 cover design, including the Project Manager's acceptance and use of the Contractor's design, plus Equipment design. Clause 24 covers people, 25 working with the Client and Others, 26 subcontracting and 27 other responsibilities. Assignment is at 28 and disclosure at 29.

Section 3: Time

Clause 31 says what a programme contains, and how the Project Manager responds to it. Clause 32 covers revisions. Clause 30 deals with starting, Completion and Key Dates, 33 access to and use of the Site, 34 stopping work, 35 take over and 36 acceleration.

Section 4: Quality management

NEC4 starts this section with quality management systems and plans at clause 40. Tests and inspections follow at 41, then testing before delivery at 42, searching and notifying at 43, correcting at 44, accepting Defects at 45 and uncorrected Defects at 46. See quality and Defects for details.

Section 5: Payment

Clause 50 covers assessing what's due, and 51 covers certificates and payment. Clause 52 deals with Defined Cost, while 53 is NEC4's final assessment. Payment rules also depend on the main Option and, usually in the UK, on Option Y(UK)2.

Section 6: Compensation events

Clause 60 has the list of events, with 60.1(1) to 60.1(21) in the core clauses. Clause 61 deals with notifying, 62 with quotations, 63 with assessing and 64 with the Project Manager's own assessments. Proposed instructions are at 65, and implementation is at 66.

Section 7: Title

Clauses 70 to 73 cover ownership of Plant and Materials, marking them, removing them and objects found within the Site. Most teams rarely need this section, but it does matter when paying for off-site items.

Section 8: Liabilities and insurance

Clause 80 lists Client's liabilities, 81 lists the Contractor's, and 82 covers recovering costs. The rest deals with insurance, including the Insurance Table in 83.

Section 9: Termination

Clauses 90 to 93 set out the termination process, reasons, procedures and payment. Read them with the Termination Table. See the termination overview.

What's different in NEC3

Topic	NEC3 ECC	NEC4 ECC
Early warnings	Clause 16	Clause 15
Contractor's cost-saving proposals	No core clause	Clause 16
Section 4 heading	Testing and Defects	Quality management
Tests and inspections	Clause 40	Clause 41
Correcting Defects	Clause 43	Clause 44
Proposed instructions	61.2	Clause 65
Implementing compensation events	Clause 65	Clause 66
Final assessment	No equivalent clause	Clause 53
Section 8 heading	Risks and insurance	Liabilities and insurance
Core compensation events	60.1(1) to (19)	60.1(1) to (21)

A tip on reading the numbers

A number on its own is ambiguous, so always say which contract you mean. Clause 65 means proposed instructions in the NEC4 ECC, but implementing compensation events in the NEC3 ECC. If you move between editions, or you're working from an old template letter, check every reference before you send it. See NEC3 vs NEC4 for a wider comparison.

Related guides

• NEC vs Other Construction Contracts
• NEC ECC Contract Overview
• NEC Contracts Explained for Beginners
• How an NEC Contract Is Structured

This guide is general information in our own words, not legal advice. Your contract and its Contract Data always govern. NEC, NEC3 and NEC4 are trade marks of Thomas Telford Ltd; Contract Status is not affiliated with or endorsed by NEC.