With the boxes, TurboTax is attempting to make sure that it gives you all the options for entering capital gains, whether they are short or long term (this changes the tax impact). If you don't know, just try picking a box and then the next screen will probably look more like what you're expecting.
I’ll try to explain in more detail:
- Box A is for short term capital gains with cost basis reported to the IRS
- Box B is for short term capital gains with cost basis NOT reported to the IRS
- Box D is for long term capital gains with cost basis reported to the IRS
- Box E is for long term capital gains with cost basis NOT reported to the IRS
- Box X is for holding period and cost basis NOT reported to the IRS
So these are not what is reported on a 1099-B (or a substitute), but rather, this allows you to pick the one that fits your situation, and then it will allow you to enter the information from your 1099-B (or substitute).
So, try to pick the box (or boxes if multiples) that fits your situation as far as short term or long term, and if the cost basis was reported to the IRS or not.
The important information from a 1099-B is the information about date acquired (box 1b), date sold (1c), the sales proceeds 1d), the cost basis (1e), and of course the tax withheld (4). TurboTax automatically can figure out if it's LT or ST.
Understand that assets held a year or less than a year will be short term capital gains (at regular income tax rates), and anything held 1 year and 1 day or more will be long term capital gains (with potentially lower tax rates).
Here is a sample 1099-B for 2014 http://www.irs.gov/pub/irs-prior/f1099b--2014.pdf
This link may prove helpful to you with questions about capital gains: http://www.irs.gov/taxtopics/tc409.html