The defer date indicates when you want a task to become available. Until that date, it won’t show up in any perspectives that are filtering out unavailable tasks. It’s a way of hiding future work so it’s not distracting you today. You’ll start to see available tasks in various perspectives as soon as they’ve reached their defer date.
The new planned date is for scheduling when you actually plan to do the task. It could be days or weeks or months later than the defer date. It doesn’t affect the status of a task, unlike defer dates which change a task from unavailable to available (or due dates which change a task to due soon and then overdue). But it can be used to make a task show up in Forecast at the scheduled time, or to have the app send you a notification to remind you about the task at that time.
If you’ve found that you’re wanting to schedule tasks, and you’ve previously been trying to use due dates for that purpose (leading to constantly pushing back due dates that didn’t get done, and desensitizing you to the important must complete on time due dates in your life), or if you’ve been frustrated trying to use defer dates to schedule tasks (which weren’t really designed for that purpose, making it easy for those dates to slip by unnoticed when life gets too busy), then you might find it easier to work with the new planned dates to help you schedule work without interfering with the work’s actual constraints.
Because planned dates don’t express a constraint, they are applied to subtasks differently than defer dates (where deferring a project defers all items within) and due dates (where a due project makes all items due). The parent item’s schedule date becomes the default for all subtasks, but you can choose to override that for any subtask and schedule it for an earlier or later date.
