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The only good news about wash sales is that your disallowed loss doesn’t just go up in smoke. Instead, it gets added to the basis of the replacement securities. When you sell them, your disallowed loss effectively reduces your gain or increases your loss on that transaction. Also, the holding period of the wash sale securities is added to the holding period of the replacement securities, which increases your odds of qualifying for the favorable tax rate (15% for most folks under the current rules) on long-term capital gains.
Example 1: Say you purchased 100 shares of XYZ Co. on Dec. 1, 2016, for $2,000. On April 1, 2017, you sell the shares for $1,200, thus incurring an $800 short-term loss. But on April 10, 2017, you have a change of heart and buy back 100 shares for $1,300. Your $800 loss is disallowed, but it gets added to the basis of the replacement shares. So your basis becomes $2,100 ($1,300 plus the $800 disallowed loss). In addition, the holding period for the replacement shares includes the Dec. 2, 2016, through April 1, 2017, holding period of the shares for which the loss was disallowed. When you file your 2017 return, report the wash sale on Part I of Form 8949, which feeds into Schedule D, since it was a short-term transaction (See the Schedule D instructions for full details on reporting wash sales).
