In order to close a short you must go to the market and acquire some securities.
Date Acquired is the date you closed the short sale.
Date Disposed is settlement date after Date Acquired. Options settle in one business day. Stocks in two.
So, your gain/loss is always Short Term, no matter how long you were short.
If your broker is reporting your transaction incorrectly, you should change the dates.
Then get another broker.
