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TimeZoneInfo.IsInvalidTime Method

Indicates whether a particular date and time is invalid.

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

public bool IsInvalidTime(
	DateTime dateTime


Type: System.DateTime
A date and time value.

Return Value

Type: System.Boolean
true if dateTime is invalid; otherwise, false.

An invalid time falls within a range of times for the current time zone that cannot be mapped to Coordinated Universal Time (UTC) due to the application of an adjustment rule. Typically, invalid times occur when the time moves ahead for daylight saving time. See the Example section for an illustration.

The value of the Kind property of the dateTime parameter affects whether dateTime represents an invalid time, as the following table shows.

DateTime.Kind property

TimeZoneInfo object (if applicable)




Determines whether the time is invalid.


TimeZoneInfo.Utc or a non-local time zone.

Converts dateTime to the time of the TimeZoneInfo object and returns false.


Not applicable.

Assumes dateTime is the time of the TimeZoneInfo object and determines whether it is invalid.


Not applicable.

Returns false.

Notes to Callers

On Windows XP systems, this method applies only the adjustment rule if the current instance is TimeZoneInfo.Local. As a result, the method may not accurately report whether dateTime is an invalid time for periods before the current adjustment rule came into effect. For more information, see the Notes for Callers section in the Local property.

In the Pacific Time zone, daylight saving time begins at 2:00 A.M. on April 2, 2006. The following code passes the time at one-minute intervals from 1:59 A.M. on April 2, 2006, to 3:01 A.M. on April 2, 2006, to the IsInvalidTime method of a TimeZoneInfo object that represents the Pacific Time zone. The console output indicates that all times from 2:00 A.M. on April 2, 2006, to 2:59 A.M. on April 2, 2006, are invalid.

// Specify DateTimeKind in Date constructor
DateTime baseTime = new DateTime(2007, 3, 11, 1, 59, 0, DateTimeKind.Unspecified);
DateTime newTime;

// Get Pacific Standard Time zone
TimeZoneInfo pstZone = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");

// List possible invalid times for a 63-minute interval, from 1:59 AM to 3:01 AM
for (int ctr = 0; ctr < 63; ctr++)
   // Because of assignment, newTime.Kind is also DateTimeKind.Unspecified
   newTime = baseTime.AddMinutes(ctr);
   Console.WriteLine("{0} is invalid: {1}", newTime, pstZone.IsInvalidTime(newTime));

.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.