A wash sale occurs when you sell an investment at a loss and then repurchase the same or a “substantially identical” investment within 30 days. The loss on the sale is disallowed for tax purposes, and the cost basis of the replacement investment is increased by the amount of the disallowed loss.
Wash sales can be used to avoid paying taxes on capital gains, but they can also be used to generate artificial losses to offset capital gains from other investments. The IRS has strict rules against wash sales, and taxpayers who engage in them may be subject to penalties.