J.S.
I had to google it and I do not practice tax, but that is a schedule prepared by partnerships. Not that I ever did our taxes in my first marriage but I believe that was the exact reason we couldn't file our personal taxes until late March. The corporation had to prepare their taxes first so that we had that schedule to do our taxes. Oh, yeah, privately held corporation. My ex was family therefore a stockholder.
So yes, they have all the time they want to supply it. I remember years where I had to drive our return to the post office. It was also the reason the same person prepared the corporate and our personal taxes. Quicker that way.
Cheryl, that link you have says mid-March.