Two comments on your formula:
If you want the answer to be a number, rather than a text string, throw away
the quotes around the "numbers".
You don't need to test for =3600, because you've already covered the cases
where D5<3600.

Your formula can therefore become
=IF(D5<360,0,IF(D5<720,5,IF(D5<1800,10,IF(D5<3600, 15,20))))

If the question you are asking is how to calculate the number of days
worked, given a start date in A5, the answer is =TODAY()-A5 (with the result
formatted as a number or general, not a date).
--
David Biddulph

"RRyan" wrote in message
...
I'm working on a vacation tracker, so far I have "start date", "today's
date", "days360",
"=IF(D5<360,"0",IF(D5<720,"5",IF(D5<1800,"10",IF(D 5<3600,"15",IF(D5=3600,"20","")))))"
(returns the number of days earned.) "days used", "days left". Is there a
way to get excel to add the correct number of days to the available days
on
the anniversary date? Or does someone already have a vacation tracker
made
that they wouldn't mind sharing?