It is an old question, but that's not your fault ;-)
The amount of your annual withdrawal should be enough to cover all of your expenses, whatever they might be. This would include any income taxes you owe each year.
"At times the world can seem an unfriendly and sinister place, but believe us when we say there is much more good in it than bad. All you have to do is look hard enough, and what might seem to be a series of unfortunate events, may in fact be the first steps of a journey." Violet Baudelaire.