Cost basis: What to do if don't have the purchase date of stocks you sold

The first step to figuring out your cost basis is to determine when your shares were purchased. That can be tricky, especially if it was a long time ago or if the stock was a gift or came in the form of an employer stock grant.

Troy Lewis, a CPA based in Draper, Utah, suggests asking the selling broker to search records for clues. Check prior-year tax documents for sales of the same stock, reflecting an acquisition date. Another way to track down the date: If the investment was a gift, perhaps a relative got the same gift and has records that show a purchase date.

If those options don't work, you may have to make an educated guess about when the stock was purchased. You can do that by going to the company's website, BigCharts, or Yahoo Finance to find historical high and low prices for that period. (They should be adjusted for any splits.)

With that information, you can then estimate your capital gains. Average the two prices, then multiply the total by the number of shares sold. That's your cost. Subtract that number from the sales proceeds to estimate your capital gain or loss.

Learn more about saving money on tax prep and getting more back in your refund with Consumer Reports Tax Guide.