What does NEC4 clause 60.1(15) mean?

Take-over is when the other side takes possession of part of the works to use it. In the NEC4 main contract the Project Manager certifies it. On an NEC subcontract your main contractor does. Both conditions must be met: the take-over comes before Completion of the whole works, and before the Completion Date. If you are late and a part is taken over after the Completion Date has passed, the clause does not apply. The other side is only taking what it should already have had. The event turns on the certificate, so get it. To rely on the clause, show the certificate, the part it covers, its date, and that both Completion and the Completion Date were later. The event comes from the other side's own certificate, so your main contractor should notify it when it certifies. If it does not, you notify under clause 61.3, and the 8-week bar does not apply. The change to the Prices, your contract price, is assessed under clause 63.1. It is the effect on actual Defined Cost up to the date of the certificate and forecast Defined Cost after it, plus the Fee. The effect is usually indirect. It can mean losing the area for access or storage, working around the occupiers, extra protection and separation, out-of-hours work, split commissioning and separate temporary services. Two things go wrong most. You treat early take-over as good news and quote nothing, then find the working conditions have changed and the 8 weeks have gone. Or the quotation includes the cost of finishing the part itself, which was always yours. Any delay to the Completion Date is assessed separately under clause 63, and that is a job for your planner.