Reaching Practical Completion on a subcontract should be a milestone for celebration. Instead, for many commercial specialists, it marks the exact moment the main contractor drops a financial bomb: a formal notice claiming hundreds of thousands of pounds in Liquidated and Ascertained Damages (LADs) for project delays. Under JCT Clause 2.23, these penalties are devastatingly simple to apply if you do not understand the rules of notice. If you miss your defensive windows, your entire profit margin can be wiped out in a single progress payment cycle.
The Main Contractor’s Practical Completion Playbook
Liquidated damages are pre-agreed, fixed weekly financial penalties written into the contract to compensate the main contractor for late completion. Main contractors frequently run a specific commercial play: they stay silent about minor site delays during the main construction phase, and then stick the subcontractor with an un-notified LAD bill right at the final account stage.
They can legally do this because standard JCT frameworks shift the entire administrative burden of proving a delay onto you. If site progress slowed down because another trade blocked your access, or because the design team delayed a drawing approval, the contract treats it as your delay until you formally prove otherwise.
The Legal Shield: Extensions of Time and Non-Completion Notices
To protect your cash flow, you must understand the two-part mechanism that triggers a legitimate LAD deduction under Clause 2.23:
The main contractor must have formally issued a Non-Completion Notice stating that you failed to complete the works by the pre-agreed completion date.
The main contractor must issue a formal notice of intent to deduct or claim LADs before the actual deduction takes place.
Your ultimate defence against this mechanism is the immediate submission of a formal notice requesting an Extension of Time (EOT). The second an event beyond your control delays your progress, you must notify the main contractor in writing, stating the cause of the delay and estimating the impact on your completion date.
The Slip-Up: Giving Up Rights via “Just Cracking On”
The biggest administrative error subcontractors make is listening to a site manager who says, “Don’t worry about the paperwork, just crack on and we will sort out the dates later.” If you do not issue your delay notices within the strict time limits set out in your subcontract, you completely lose your legal right to an Extension of Time. Google is currently indexing pages where we highlight this exact reality. Without an EOT, the contractor has full legal rights under Clause 2.23 to strip your profit margin clean away to cover their own delays.
How to Secure Your Position
Never let a delay notice go unwritten. Keep a clean, written paper trail of every site delay, variations packet, and access blockage. Ensure your extension of time requests reference specific contractual causes of delay (Relevant Events) to keep the main contractor on the defensive.
The Combined Call-To-Action (CTA) Blocks
Main contractors routinely look for administrative slip-ups to offset their own project overruns against your retention and payments. Do not let hidden delay notices strip away your hard-earned margins. Before you sign your next draft agreement, use the JCT contract checker on Trade Contracts Simplified to instantly identify predatory liquidated damages rates, unfair notice windows, and hidden completion traps before they hit your company cash flow.
To map out your exact financial exposure before stepping on-site, you can also run your numbers through my standalone UK Day Rate Delay Calculator. This dedicated platform tool allows you to plug in your standard team day rates and contrast them directly against your contract’s LAD terms, showing you exactly how many days of ungranted delay it takes to completely wipe out your projected trade profit margin.
Behind the Tech: Built for the Trades
I custom-built this automated contract scanner and day rate tool through my parent technology consultancy, Your Tech Neighbour. Operating out of Lyde Green, I specialise in building straight-talking, practical AI tools and custom workflow automation systems that eliminate manual admin bottlenecks for UK construction firms, commercial specialists, and independent tradespeople.
If your trade business needs a custom software solution, automated client onboarding pipelines, or a tailored AI assistant built specifically for your day-to-day operations, you can explore my full technology capabilities or schedule a local face-to-face chat at Your Tech Neighbour.