DateTimeOffset Represents a point in time, typically expressed as a date and time of day, relative to Coordinated Universal Time (UTC) it provides a greater degree of time zone awareness than the DateTime structure. See it here- http://msdn.microsoft.com/en-us/library/bb546101.aspx.
DateTimeOffset Overcomes the drawback of DateTime. It expressed as a date and time of day, relative to Coordinated Universal Time (UTC). For Example:
Given 4/18/2013 11:00:00 AM means absolutely nothing if you don’t have a reference point. That could be 11:00:00 AM anywhere in the world. DateTimeOffset contains information about the timezone you are dealing with, which makes all the difference in THE WORLD!