More on this...
So if you buy a boat for $300 and sell it on Ebay for $1,000 - even if for cash - you'd better have the receipts to prove what you paid and what you put into it or the IRS will want the tax on the whole $1,000.
From Slashdot...
"In 2009, $60 billion worth of items were sold on eBay, meaning 'extra' money for many sellers, whose activities may provide them with taxable income. Now the Washington Post reports that beginning next year, a new law will require 'the gross amount of payment card and third-party network transactions to be reported annually to participating merchants and the IRS.' Also, for 2011 tax returns, 'taxpayers who annually sell more than $20,000 worth of goods and have more than 200 electronic transactions' will receive a new IRS form, known as 1099-K, for reporting the proceeds. The new tax issues shouldn't be a concern for people who sell just a few small items online for less than they paid for them, because as the IRS points out, income from auctions that resemble a garage or yard sale 'generally' isn't required to be reported. But if an online garage sale turns into a business with recurring sales and purchases of items for resale, it may be considered an online auction business. 'Generally, transactions resulting in a gain are reportable, regardless of whether the taxpayer is conducting a business,' says Gil Charney, principal tax researcher at The Tax Institute at H&R Block. The real reason behind the law is simple: Research shows taxpayers do a much better job of reporting taxable income when they know the IRS is receiving information about their transactions."