Unlike most of the other methods that add a single time interval unit (such as minutes or days) to a date and time value, AddMonths does not enable you to add fractional parts of a month. To add a time that consists of other time units in addition to months to a DateTimeOffset object, use the Add method.
This method returns a new DateTimeOffset object. It does not modify the value of the current object by adding months to its date and time.
Universal Windows Platform Available since 8 .NET Framework Available since 2.0 Portable Class Library Supported in: portable .NET platforms Silverlight Available since 2.0 Windows Phone Silverlight Available since 7.0 Windows Phone Available since 8.1