Practical Completion
The point at which the works are complete enough for the employer to take possession and use them for their intended purpose — notwithstanding minor outstanding items. It is a judgement, not an arithmetic test.
What makes it contentious is that no standard form defines it precisely. Minor snags do not prevent it. Anything that prevents beneficial use does. Between those two poles lies a great deal of argument, and the argument is expensive because so much hangs off the date — liquidated damages stop, the defects liability period starts, retention becomes partly releasable.
The practical defence is the outstanding-works list, agreed and attached. It converts "is it complete?" into "is anything on this list preventing use?", which is a far more tractable question and one that can be answered by walking the building.
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