IRS tax question

[GregMitch34]

Bill--

Thanks for your lengthy and mostly clear reply. But perhaps one example might help a little. Let's say you sell 30 cards via an AH for let's say $30,000. They take their $6000 which I can you report as fee or whatever. Of the $24,000 you get you judge that you only made about $4000 above what you paid for those same cards. However, each card is different--on some you made big profit, on others loss; some you purchased ten years ago, others in past year. The ones from long ago you may not even recall what you paid so you are guessing. So what do you report here? Just a straight $4000, or $24,000 minus whatever, or you submit a breakdown of all 30 cards as best you can? Thanks.