Returns a new DateTime that adds the specified number of months to the value of this instance.
Type Reason ArgumentOutOfRangeException
The months parameter is less than -120,000 or greater than 120,000
The DateTime.AddMonths(int) method calculates the resulting month and year, taking into account leap years and the number of days in a month, then adjusts the day part of the resulting DateTime object. If the resulting day is not a valid day in the resulting month, the last valid day of the resulting month is used. For example, March 31st + 1 month = April 30th. The time-of-day part of the resulting DateTime object remains the same as this instance.