How to use due dates in Kanban Tool?

To use a due date field on your Kanban cards, first make sure the field is enabled in Settings - Card Template, accessible from your board view. The board settings page

Once selected as part of your Card Template, a due date field will be visible on task cards: Editable due date inside a task

You can also see the due date without opening the task - it will appear when you hover the mouse pointer over the calendar icon. Also, when the due date has 9 or fewer days to go, the remaining number of days will display right next to the calendar icon. Due Date Preview

Once the date is up, there will be a distinct red 0 or - # days” staring at you from the card.

Due dates are also marked in the Calendar Widget (when enabled from Settings - Power-Ups). Calendar widget - due dates visibility

Related: You may also be interested in using the separate start date field.