Accessiblity

It depends on how the PDF was created and/or remediated. Here is some background information.

The law in the United States that requires accessible ICT is Sec. 508 of the Rehabilitation Act of 1973, not the "ADA" which is the Americans with Disabilities Act, a different piece of legislation.

Sec. 508 doesn't state how to make a PDF compliant, nor does it state what makes a PDF compliant. The law is posted here on the US government's website https://www.access-board.gov/guidelines-and-standards/communications-and-it/about-the-ict-refresh 

Instead Sec. 508 refers to the current international accessibilitly standards, which are WCAG 2.0 and PDF/UA-1 (which is the preferred standard for PDFs).

So if you'd like to know if a PDF is compliant, look at the PDF/UA-1 standards and ensure that it meets the specs. Here's a free syntax guide about PDF/UA-1: https://www.pdfa.org/resource/tagged-pdf-best-practice-guide-syntax/ 

You can also use a software checker, but none adequately test for everything. We recommend using 2 free checkers to see if your PDF contains the basic accessibility requirements:

• Internal accessibility checker in the latest release of Adobe Acrobat Pro.
• PAC3, a free program from Axes4, a Swiss foundation https://support.axes4.com/hc/en-us/articles/201957988-PDF-Accessibility-Checker-PAC- 

Our firm recommends using both testers to check PDFs for Sec. 508 compliance. A human using assistive technologies should also check the PDF for compliance.

Just in case you need it, here's an excellent free online series from Adobe about making accessible PDFs:

https://adobe.lookbookhq.com/acrobataccessibility  It's an excellent series hosted by Adobe's Rob Haverty who is part of Adobe's accessibililty team.