I assume the gain is section 1231 appearing on line 10.
is this a real estate venture then the 743(b) adjustment because of the nature of the activity will be passive
if this is another type of business venture (probably there should be a gain or loss on line 1 of part III) then do you materially participate? if so that box "materially participates" needs to be checked otherwise the 1231 gain is passive because you are a passive investor
if the gain is on lines 8 or 9 - these are nonpassive regardless of anything else
check to see if the gain is flowing to form 4797 Part 1 which then flows to schedule D
check to see if the 743(b) adjustment flows to schedule e page 2
