# NEC4: How to approach Option Z / amendments

This webinar explores when and how to draft Option Z additional conditions in NEC4 contracts, covering best practice principles, common pitfalls, and the balance between cost certainty and value for money. Ben Walker and Glenn Hide walk through real examples of Z clauses that can cause problems, from reducing time bar periods to deleting mutual trust obligations, with practical guidance on testing amendments before implementation.

## Key Takeaways

### Follow Best Practice Before Drafting Any Z Clause

Before putting pen to paper, ask why the change is needed, what problem it solves, and whether the issue can be addressed through scope or contract data instead. Flowchart the change against existing NEC processes to catch conflicts and unintended consequences before they reach tender.

### Share Your Reasoning With the Supply Chain

Publishing the thinking behind proposed amendments helps bidders price risk appropriately and builds trust. Contractors interpret unexplained changes as a signal that the client will be difficult to work with, which limits competition and increases tender prices.

### Balance Cost Certainty Against Value for Money

Clauses that transfer all scope errors to the contractor may provide budget certainty, but they increase tender prices and can shrink the pool of willing bidders. Consider keeping contingency for errors and paying only when issues actually arise through the compensation mechanism.

### Test Z Clauses Against Abrahamson Principles

Allocate risk to the party with most control, who can transfer the economic risk, stands to gain the most, or where the loss falls naturally. If reversing the positions would make you uncomfortable signing the contract, the clause probably needs rethinking.

## Session Transcript

### 00:00 - Introduction

Good afternoon everyone and welcome to our sixth webinar. Today's topic hopefully you're going to enjoy this session and yeah we're getting into the deep dive of Z clauses and how they should be managed and introduced.

### 02:30 - Why Z Clauses Exist and NEC's Modular Structure

... we have these core clauses. We have main option clauses for payment. We have dispute resolution options ... option Z, which is all about these additional conditions of contract.

### 06:45 - Best Practice Process for Drafting Additional Conditions

... it's very hard for any CD authors of contracts to police Z clauses. Because at the end of the day, no client has to go back through NEC ... to have permission to change the clause.

### 15:20 - Three Types of Z Clause

So when I look at a contract data part one for the first time ... I try to calm myself by thinking there are probably three buckets here.

### 18:40 - Constraints: Scope Versus Z Clause

So here we've got an example of a constraint. No work shall be carried out between ten p.m. and seven a.m.

### 21:15 - Transferring Scope Errors to the Contractor

... the contractor is deemed to have examined all of the scope documents...

### 28:10 - Reducing Time Bar Periods

... reducing the timescale that the contractor's got to notify a CE ...

### 33:45 - Deleting Compensation Events for Late Replies

This one's a brief one to explain. The client here wants to delete certain things around the project manager...

### 36:20 - Deleting Mutual Trust and Cooperation

... on training, we talk about the obligation to act in a spirit of mutual trust and cooperation.

### 37:50 - Abrahamson Principles for Risk Allocation

... A risk should be allocated to a party if they have the most direct control...

### 42:00 - Style Crimes

... NEC is written in straightforward plain language. It's written in present tense, active voice...

### 45:30 - Conclusions and Useful Resources

So remember why, think about the why, and share that reasoning. If you're going to change a contract, the reason why you want to change it should be communicated, ideally pre-tender.

## Audience Q&A

- **Can I reduce the eight week time bar period for notifying compensation events?**

- **Should constraints like working hours go in Z clauses or the scope?**

- **What happens if a Z clause contradicts another part of the contract?**

- **Is it ever appropriate to delete clause 10.2 on mutual trust and cooperation?**

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