DateTime.AddMonths Method

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Returns a new DateTime that adds the specified number of months to the value of this instance.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)


Public Function AddMonths ( _
    months As Integer _
) As DateTime
public DateTime AddMonths(
    int months


  • months
    Type: System..::.Int32
    The number of months to add. This value can be positive or negative.

Return Value

Type: System..::.DateTime
An object whose value is the sum of the date and time represented by this instance and months.


Exception Condition

The resulting DateTime is earlier than DateTime..::.MinValue or later than DateTime..::.MaxValue.


months is less than -120,000 or greater than 120,000.


This method does not change the value of this DateTime object. Instead, a new DateTime object is returned whose value is the result of this operation.

The AddMonths 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.

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0


Windows Phone

See Also


DateTime Structure

System Namespace