I have avoided using the tagging system in Acrobat for years I had hoped it had improved from my last attempt. I have been designing any accessible form in Livecycle which is amazingly simple to do in. Also I can updated the PDF without starting over. With these forms I have to use Quark then make fillable forms in Acrobat.
Is there any advice to trying to tag a complex PDF with fillable fields?
I tag the form and the order it has decided is all over the place, so I start rearranging the form and about every 10 to 20 tags it just decides for what every reason that a previous tag should now be in a different place. With 100's of tags this is head banging slow and frustrating.
Are you using the Order pane to set the reading order? If so I recommend using the Tags pane instead. As long as the tab order is set to "Use Document Structure" the order of the tags defines the reading order. The Order pane works by rearranging the tags, but sometimes not very well. I get much more reliable results by rearranging the tags directly. If you want a tool to let you visually verify the order is set correctly, the Preview feature of the free PDF Accessibility Checker (PAC) from the Swiss foundation Access for All does a much better job than Adobe's Order pane or Reflow View.
a 'C' student
As a C student mentioned, use the Tags panel. You might want to go through and artifact all the unwanted tags first, so there are fewer to sift through.