Milestone
A defined event in a project marking the end of a phase or acceptance of a deliverable. Milestones trigger stage payments, authorize next phases, or confirm handover. They are completion events, not tasks or durations.
A milestone is a specific, identifiable event that marks the end of a project phase or the formal acceptance of a deliverable. Unlike a task, a milestone has no duration - it is the point at which something is complete and something else can begin. When a milestone is reached, a defined consequence follows: a payment becomes due, the next phase is authorized, or a deliverable formally transfers between parties.
Why Milestones Matter in Project-Based Businesses
In construction, milestones include events such as foundations poured, structural frame complete, practical completion certified, and defects liability period ended. Each one in a payment schedule releases a defined percentage of the contract value. Missing the milestone means the invoice cannot be raised; raising the invoice before the milestone is confirmed risks a dispute that delays payment further.
In AV integration, commissioning sign-off is the milestone before the final 20-30% payment can be invoiced. In office furniture, the installation acceptance sign-off unlocks the snag retention invoice. In electrical work, the issue of the Electrical Installation Certificate authorizes the final invoice.
The key discipline is defining milestones in writing before work begins, tied to a specific observable event rather than a calendar date. A date can pass without the work being complete; a defined completion event cannot be ambiguous in the same way.
Milestones and Stage Payments
Every stage payment should be linked to a milestone. "30% on completion of second fix" is a milestone-based payment. "30% payable in month 3" is calendar-based and creates cash flow risk if the work runs ahead or behind schedule.
Zigaflow's project tracking tool allows milestones to be recorded against jobs so the team can monitor completion status and raise invoices at the right point in the project lifecycle.
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