You will need to enter a "Date Acquired".
One option is to enter 'various'. Various covers all the dates you made the acquisition. It is fine to use various so long as all the sold dates are more than one year after purchase date of the specific security.
If the "Date Acquired" field is blank on your Form 1099-B, it means the Payer didn't have that information. You would need to provide an answer from your records or enter a date that is consistent with the holding period.
If you held the security for more than 1 year, then enter a "Date Acquired" that is more than 1 year before the date you sold the security.
If you held the security for less than 1 year, then enter a "Date Acquired" that is less than a year before the date you sold the security (1/1/2015 will work).
If you aren't sure how long you held the security, try looking for the "Box" or "Code" on your 1099-B.
If Box A or B is checked, then the holding period was less than one year.
If Box D or E is checked, then the holding period was more than one year.
