The following video is a demonstration of Adobe's Accessibility Check method. Running this should be your first step if you have any doubts about whether the PDF has had any remediation (accessibility fix) work done to it. If you run the check and get an error message that the PDF is untagged, please proceed to the Make Accessible Action Wizard method further down the page (video for "Basic PDF Accessibility"). 

The following video demonstrates how to run Adobe's Make Accessible Action Wizard. This method should be used if you are certain there has been no work done already to make the PDF more accessible. For example, if you get an error message in Ally that the PDF is untagged or scanned (but not OCRed). If you are not sure, please use the Accessibility Check in Adobe instead (video above). 

There are two errors that will consistently appear when you run either process in Adobe Acrobat DC Pro, because they need to be checked manually each time. One is reading order and the other is color contrast. Below, you will find video instructions for how to assess and clear both errors.