By default, enrolled students have access to quarter-based courses one week before the start of the course through one week after the course ends.  Semester-based courses open to students on the start date of the course and are available until one week after the course ends.  These dates are set automatically via integration from Banner to Canvas.

The course becomes read-only to students after the end date.  To allow students to continue having full access to the course, or in the case you have a student who needs to resolve a status of Incomplete, you can modify the end date of the course by going to Settings, changing Participation from Term to Course, and then setting a Start and End Date. The Start Date can be set as the normal term start date, and the End Date can be set to however long after the end of term date you need.