This exercise has nothing to do with taxes. Just want to get that out of the way because of the misleading headline.
Start with an urban legend. Anything will do. If you have problems coming up with one, google is your friend, as is snopes.com. Poke around a bit until you find one you like. Bloody Mary, Sasquatch, JFK assassination conspiracies, what have you. Conspiracy theories are fine, too.
Take the legend you've chosen and break it down a bit. Why is this particular legend or myth so compelling? What keeps it in our minds.
Write a poem comparing it with issues in your own life or your history. Weave it into and out of your life. Maybe acknowledge how sketchy it might really be, or embrace it and dive in feet first. Your choice.
Check out Sherman Alexies The Sasquatch Poems over at Zyzzyva.