Michael Phelps' estimated worth is around $50 million -- so, by our math, he should be able to afford the $20K he owes the State of California. But alas, like a Michael Jackson legal bill, the debt remains unpaid. According to a tax lien filed last year -- which is still active -- the Golden Boy owes the State of California $23,289.16 for tax returns back in 2005 and 2006. If you want to make a donation to help Michael Phelps, just buy a Speedo swimsuit, Omega watch, a PowerBar, use your Visa card, switch your long distance to AT&T, ... hell, just do anything -- Phelps probably endorses it. Click below to see more stars who've had tax liens!