Player & Crazy Larry,
CL, Player is correct about the shorting. The other misunderstanding is about "what if bk and you don't have to cover".
IRS code says that the moment a stock becomes bk, worthless or non-liquid, then you owe the taxes on your short position, if any are due.
IRS is slow, but they are thorough on checking these small points. They like compound interest.
Just my comments
1260