Milestone

What it means

A milestone is a point in time of zero duration that confirms a state reached: a design approved, a work handed over, an operation live. It is neither a task nor a deadline in itself; the task takes time, the milestone only records that it is done.

It only means anything when it carries an acceptance criterion and a single owner. Without those it is a dot on the roadmap at which supplier and customer part company over what the word done actually covers.

Internal and contractual milestones need to be kept apart. An internal one helps the team manage the work and can be moved by the project lead. A contractual one is agreed with the customer, carries a payment or a penalty, and changing it takes an amendment to the contract. When the two are mixed in one plan without labels, a slip in an internal date easily turns by mistake into a promise to the customer.

How it works in practice

In a plan milestones are drawn as points on the Gantt chart and separate the phases of a project. A good milestone names a state, not an activity: not testing, but the version the customer accepted on the strength of testing.

In a contract for work a milestone usually triggers a payment and the release of retention. A partial supply also fixes the tax point for VAT, so a milestone is a tax event as much as a project one.

At year end we ask the client for the list of milestones the customer accepted in writing by the end of the period. Accepted parts go to revenue, while work in progress between milestones under a contract for work is usually reported as work in progress rather than sales, so the result for the year matches what has actually been handed over.

What to watch out for

A milestone with no written acceptance criterion is a dispute waiting to happen. The supplier treats it as met and issues an invoice, the customer does not; VAT stated on an invoice still has to be paid over when acceptance is refused, so the company parts with tax on money it will not see for months.

The other extreme is a single milestone at the end of a long project. The supplier then funds the work for months out of its own cash flow, and every delay by the customer in accepting pushes back the whole payment. Splitting it into several smaller milestones with partial payments spreads that risk.