Tom Ogilvy wrote:
Public Function LeapYear(yr as Long) as Boolean
LeapYear = (month(date(yr,2,29)) = 2)
End Sub

I was going to offer something similar (subtract 1 from 3/1 of the year
to see if the day is 28 or 29). However, basing the leap year decision
on whether the year has a 2/29 date appears to incorrectly identify
1900 as a leap year? EXCEL's date function claims there is a date of
2/29/1900.

Plus, it only works back to 1900. Which may or may not be a problem,
depending on how it is being used.