As a general rule, you determine whether you have short-term or long-term capital gain or loss on a short sale by the amount of time you actually hold the property eventually delivered to the lender to close the short sale.
Example. Even though you do not own any stock of the Ace Corporation, you contract to sell 100 shares of it, which you borrow from your broker. After 13 months, when the price of the stock has risen, you buy 100 shares of Ace Corporation stock and immediately deliver them to your broker to close out the short sale. Your loss is a short-term capital loss because your holding period for the delivered property is less than 1 day.
Special rules. Special rules may apply to gains and losses from short sales of stocks, securities, and commodity and securities futures (other than certain straddles) if you held or acquired property substantially identical to property that sold short. But if the amount of property you sold short is more than the amount of that substantially identical property, the special rules do not apply to the gain or loss on the excess.
Gains and holding period. If you held the substantially identical property for 1 year or less on the date of the short sale, or if you acquired the substantially identical property after the short sale and by the date of closing the short sale, then:
Rule 1. Your gain, if any, when you close the short sale is a short-term capital gain, and
Rule 2. The holding period of the substantially identical property begins on the date of the closing of the short sale or on the date of the sale of this property, whichever comes first.
Losses. If, on the date of the short sale, you held substantially identical property for more
than 1 year, any loss you realize on the short sale is a long-term capital loss, even if you held the property used to close the sale for 1 year or less. Certain losses on short sales of stock or securities are also subject to wash sale treatment. For information, see Wash Sales, later.