If I sold a put in 2009 that expired worthless in 2010, is this a short term capital gain in 2010? I'm going to my tax person soon, but just want to understand this.
Gain is reported as of the date the put expires. See the OPTIONS section at: http://www.irs.gov/pub/irs-pdf/p550.pdf
What sucks is the IRS double taxes you on the puts. If you sell a put with a strike of 10 for 1 dollar in premium, if you get the stock put you have to change the cost basis to 9 and still pay tax on the 1 dollar.
It's even worse than that. It's triple taxation!!!! You amass an estate and upon your demise, the Death Tax takes even more of your money. When all is said and done, the gubbermint gets more than you make so it's really a waste of time trying to trade.