NEC4 Key Date

A Key Date under NEC4 is a date by which the Contractor must have completed Conditions stated in the contract, so that the Client or another party can proceed with their own work. It is not the same as a milestone. A milestone is typically a status checkpoint; a Key Date is a contractually enforced completion obligation. Failing to meet a Key Date triggers financial consequences under the contract — specifically, the Client can recover the additional cost of the delay caused to other work that depended on the Key Date being met.

Key Dates are used on multi-contractor programmes where the work of one contractor interlocks with another, and on programmes where the Client needs to enter the work site at defined points for their own activities. A typical example is a station refurbishment where Key Dates mark the completion of each platform back to operational state, enabling the train operator to resume service while the next platform is worked on.

For project controls, Key Dates need to be treated with the same schedule discipline as the Completion Date — tracked explicitly, assessed for impact in every compensation event quotation, and visible in monthly reporting. A Key Date that slips without formal assessment is a commercial liability waiting to surface at dispute. The Accepted Programme should show every Key Date as a hard marker, and the schedule logic that drives each Key Date should be transparent and defensible.