As Tom has indicated in his entry above, "It's impossible for anyone here to answer your particular question "definitively." ". For your question, "the Acquired date and cost Basis" depends on what has been sold and how it was acquired. If this is just a sale of a security which you purchased in a single transaction on some prior occasion and the broker that's made the sale has not supplied the date and cost from the original transaction, then you'll need to consult the settlement statement (or account statements) from when you made the purchase. If you're selling an aggregate quantity of shares which were acquired on different dates, for varying purchase amounts, then you'll need to gather this from the separate settlement statements you received when making these purchases (which should also appear on you brokerage's account statements). You would then report the sales for each set of securities using the corresponding date and cost. The trickiest situation is when you've sold a mutual fund which you've purchased in different amounts at different times and which has then reinvested the dividends the fund pays to add to the shares you own. In this case I'd refer you to the vast collection of on-line articles you'll uncover by Google'ing "How do you calculate the cost basis for a mutual fund over a long time period" -- start with www.investopedia.com.
