If you look at an "official" 1099-B:
https://www.irs.gov/pub/irs-access/f1099b_accessible.pdf
you'll see there's a Box 1g for "adjustments" and a Box 1f for a
"code."
Those two boxes are there for the broker's use only. They are
not there for you to "fix" problems with the 1099-B.
IF there is anything in Box 1g THEN there must be a code in
Box 1f and the only acceptable codes are:W” and “D”.
So, if you entered something in Box 1g, or the broker, (in error), put
something like "$0.00" in there, or even if there's some non-printing
characters in there, maybe caused by a bad .TXF file you imported, then
TurboTax insists there be a code in Box 1f.
The fix here is to go back to that trade and make sure Box 1g is completely
blank. If that doesn't fix things then completely delete the trade and
re-enter it manually, making sure to leave Box 1g blank.
