> ## Documentation Index
> Fetch the complete documentation index at: https://leancpm.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Late Dates

> The latest possible dates a task can start and finish

Late dates are calculated in the [backwards pass](/calculating_schedules#backwards-pass-calculate-late-dates).

Late dates cannot be calculated for a task path (a set of tasks connected by dependencies) that doesn’t eventually lead to a Milestone.

## Late Start

`late_start`

The latest date a Task can *start* is based on when its [blocked tasks](/terms/dependencies) are finished or started, depending on the dependency type (series or parallel).

## Late Finish

`late_finish`

The latest date a Task can finish is based on when its dependencies are finished and its duration.

## Milestones

Unlike Tasks, [Milestones](/terms/milestone) have a single `early_date` field. This is the soonest a Milestone can occur.

<Callout title="Legacy CPM" type="warn">
  In legacy CPM, Milestones have an Early Start and an Early Finish, but depending on the type, only one is used.
</Callout>