I've just now run into the same problem as everyone else here. I did summarize my brokerage transactions on form 8949, and some of them included data that was not given to the IRS by my broker (it says that on my 1099B). So I understand why the IRS might want more details than a simple summary number.
But my complaint is that the first time I saw any notification of this situation was AFTER I had already e-filed. Couldn't there be a notification/warning about it while entering form 8949 data into Turbotax, which I did weeks ago and assumed everything was ready to file?
And who knows if I'm also supposed to mail the same supporting docs to my state??? (At this point it ain't happening.)
