You can use the IsDate() function to test for the existence of a Feb 29 in that year, for example
IIf(IsDate("29/2/" & Year(InputtedDate)), "Leap year", "Not leap year")
You can even build your own function in a module, for example
Public Function IsLeapYear(InputtedDate As Variant) As Boolean
If Not IsDate(InputtedDate) Then
IsLeapYear = False
ElseIf Not IsDate("29/2/" & Year(InputtedDate)) Then
IsLeapYear = False
Else
IsLeapYear = True
End If
End Function