To Mark a Task as Requiring Rework

You can mark any task in the Work in progress or Completed folder as requiring rework. This moves the task back to the Inbox, where you can accept it, reject it, or delegate it.

Open the Explore tab (View > Explore).
Click the Work Exchange icon.
Expand the Work in progress or Completed folder and select the task you want.
In the action bar, first click the Cancel Active Task icon, then click the Rework icon.
The Please Select the Task to Rework dialog opens. This dialog lists the selected task, plus any other tasks that are related to the selected task (in case you want to rework a related task instead of the originally selected task).
In the dialog, select the task you want and press the <Tab> key.
Enter a reason for reworking the task and click OK.
The selected task is moved from the Completed folder to your Inbox, and the task that was in your Inbox is moved back to the Forthcoming folder.

If email notifications are configured, an email explaining why the task is being reworked is sent to everyone involved in the work task.
Now you can go to your Inbox and accept, reject, or delegate the task.

Note: If you mark a task as requiring rework before you cancel the active task, the task still moves to your Inbox, but it has a warning that the active task must be cancelled before it can be accepted and worked on again.