text: You do have to wait.  It is called "wash" rule.  Lets say you bought stock at $100 and now sell it at $50.  You just got out with $50 loss.  Because it was a two way transaction (buy/sell) you can take that loss and use it to push down your income for the year thus avoid paying more taxes.  However if you buy the stock back within 30 days, you are no longer allowed to take that loss and use it to offset your income.  REason?  Many investors have paper losses but you can't use them to offset income.  Real losses you can.  This rule was designed so the traders/investors don't "fake" losses by basically resetting the cost basis of the stock.\n\nRival\n\nPS.  You can buy stock within 30 days after you sell it but you waive your right to use the loss (if you selling at loss not at gain :)  ) against your ordinary income.