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Applies to: 
Calculated column
Calculated table
Measure
Visual calculation
Checks whether a value is a date / time, and returns TRUE or FALSE.
Syntax
ISDATETIME(<value>)
Parameters
| Term | Definition |
|---|---|
value |
The value you want to test. |
Return value
TRUE if the value is a date / time; otherwise FALSE.
Remarks
- This function is not supported for use in DirectQuery mode when used in calculated columns or row-level security (RLS) rules.
Example
The following DAX query shows the behavior of ISDATETIME.
EVALUATE
{
IF ( ISDATETIME ( 42 ), "Is datetime", "Is not datetime" ), // RETURNS: Is not datetime
IF ( ISDATETIME ( "42" ), "Is datetime", "Is not datetime" ), // RETURNS: Is not datetime
IF ( ISDATETIME ( "2025-07-01" ), "Is datetime", "Is not datetime" ), // RETURNS: Is not datetime
IF ( ISDATETIME ( dt"2025-07-01" ), "Is datetime", "Is not datetime" ), // RETURNS: Is datetime
IF ( ISDATETIME ( DATE ( 2025, 7, 1 ) ), "Is datetime", "Is not datetime" ) // RETURNS: Is datetime
}