About Task Calendars

Note: Task Calendars have no impact to resource capacity. A user's capacity is determined by the workweek calendar to which the resource is assigned.

When a project manager creates or edits a task, PPM uses a calendar to determine what dates are valid for Planned Start and Planned Finish. If you try to set either on a date that is not a working day in the calendar, the date is pushed forward to the first valid working date, based on the calendar.

The calendar used by PPM and the impact the calendar has on a task depends on whether or not the manager explicitly chooses a calendar:

Default Enterprise Workweek Calendar—This is the default for a task. When the workspace manager has not explicitly selected a calendar, the task is scheduled based on the default enterprise workweek calendar.

Your PPM administrator defines the default calendar, along with any other workweek calendars applicable to your organization. As part of this definition, the administrator can create and assign global nonworking time (company holidays, for example) to the calendar(s). When a task uses the default enterprise workweek calendar, global nonworking time is taken into account on saving the task. This means that the days you can specify for Planned Start and Planned Finish, and the actual date of Planned Finish, are limited by the valid work days on the calendar, and a task that spans a day that is not a working day (a weekend day for example) or has a Planned Finish that falls on a non-working day, will be adjusted, with the finish date pushed out to account for any non-working days.
Task Calendar—This requires the project manager (or other user with edit permission on a task) to explicitly select a calendar for the task. When the manager selects a calendar from the list of calendars in the Planned Start or Planned Finish calendar pop-up, the selected calendar takes precedence over any default workweek calendar or resource calendar(s).

The scheduling of the task takes into account global nonworking time (if applicable) and ignores any calendars associated with any assigned resources. You might want to explicitly select a task calendar if you know the task will be worked on during days that are not standard work days (as defined by the default enterprise workweek calendar). For more information, see Why Select a Task Calendar (opens in a popup).

Once a task calendar is associated with the task, all default behavior (default workweek calendar or resource calendar) is overridden. To reset the calendar to default behavior, see Resetting Default Calendar Behavior (opens a popup).

Tasks and Calendars - Some Things To Be Aware Of

Only in the Task List Add/Edit Panes—You can only specify a task calendar from the workspace-level Task List Add and Edit panes. When using the old popup window to add or edit a task (from the global Tasks application for example), the default behavior (either default enterprise workweek calendar or resource calendar(s)) is the only option.
Order of Precedence—The order in which you select a date and a calendar impacts how PPM determines a valid date. If your selected date is pushed out due to a non-working day in the default calendar and you subsequently select a different calendar, double-check your dates to make sure they have not been pushed out beyond where you intend. They will be shifted to the next valid date after their current date.
Parent Tasks Duration—The duration of a parent task is always calculated using the default enterprise calendar. As a result, if any child tasks is using a non-default calendar (either resource calendar or task calendar), there may appear to be a discrepancy between the duration of child tasks, and the duration shown for the parent task.
Deleted Calendars—If a resource or task calendar is deleted, any existing tasks using that calendar will be "out of sync" (they may include invalid dates) until the task is edited. An edit of any kind will force a readjustment of dates using the default enterprise workweek calendar or resource calendar(s).