Since all documents are filed with the IRS, you will want to enter all tax documents with the year to which they are issued. If the capital loss is greater than the capital gains you are able to deduct the difference as a capital loss up to $3000 if married filing jointly (or $1500 if married filing separately) per year, even if you do not have the ordinary income to offset it. If the amount is greater than the yearly limit, then there are elections within TurboTax for what to do with the carryover amount if you cannot use the entire amount this year.
For more information about the treatment of capital loss, please see page 37 of the link below:
http://www.irs.gov/pub/irs-pdf/p544.pdf
Edited: 03/15/2017
To enter a 1099-B, follow the steps below:
https://ttlc.intuit.com/replies/4789365
