If you are using the calculation for recent years then the equation above will work. But if you were going back a couple hundred years or forward a couple hundred years then you would need something else.
1. Years divisible by four are leap years, unless...
2. Years also divisible by 100 are not leap years, except...
3. Years divisible by 400 are leap years.
'Check to see is this is a Leap Year
Dim Date1 As Date, Date2 As Date, IsLeapYear As Boolean
Date1 = "January 1," & Year(Now()): Date2 = "December 31," & Year(Now())
If DateDiff("d", Date1, Date2) = 365 Then
IsLeapYear = True
MsgBox " This is a Leap Year"