A wash sale occurs when you sell or trade securities at a loss and within 30 days before or after the sale you:
Buy substantially identical securities,
Acquire substantially identical securities in a fully taxable trade, or
Acquire a contract or option to buy substantially identical securities.
Internal Revenue Service rules prohibit you from deducting losses related to wash sales. For more information about wash sales, read IRS Publication 550, Investment Income and Expenses (Including Capital Gains and Losses).