Intercalary Traditional Cache

Today is a day that is inserted in the calendar to harmonize it with the solar year.  This doesn't happen often but isn't to dificult to figure out:

if (year is not divisible by 4) then (it is a common year)
else if (year is not divisible by 100) then (it is a leap year)
else if (year is not divisible by 400) then (it is a common year)
else (it is a leap year)

Even if it isn't a leap year, you can still get the cache on any day.

*  BYOP