A common process when managing Tasks in Outlook is to set the Start Dates & Due Dates, and change these dates when needed. The logic in Outlook does not allow you to set a Due Date to a date before the Start Date or set the Start Date to a date after the Due Date. This blog post will describe the results you can expect for various scenarios when you change the Start and Due Dates of a Task.
Scenario #1. You change the Due Date of a task before the Start Date.
Result:
Outlook for Mac 2011 & Outlook 2016 for Mac – The Start Date is automatically moved to be the same as the Due Date.
Outlook 2010 & 2013 – You receive an error “The due date of a task cannot occur before its start date.”
Examples:
Windows Outlook 2013 or 2010:
| The Tasks Start Date is April 1 and the Due Date is April 5. |  |
| You try to change the Due Date to March 30. |  |
| You receive this error message. |  |
Outlook 2016 for Mac or Outlook for Mac 2011:
| The Tasks Start Date is April 1 and the Due Date is April 5. |  |
| You change the Due Date to March 30. The Start Date changes to March 30 automatically. |  |
Scenario #2: You change the Start Date of a Task that also has a Due Date set.
Result:
All Outlook versions: The Due Date automatically changes preserving the duration of the task.
Example:
| You have a task that starts on April 1 and is due on April 5. |  |
| You then change the start date to April 3, and the Due Date automatically changes to April 7. |  |
Scenario #3: The Start Date of a task is initially set to None with a Due Date set, and then you set the Start Date to a date later than the Due Date.
Result:
All versions of Outlook: The Due Date will change to the same date as the new Start Date that was set.
Example:
| The Task Start Date is set to None, and the Due Date is set to April 5. |  |
| You set the Start Date to April 10 |  |
| The Due Date is automatically changed to April 10. |  |