It’s always better to plan ahead for accessibility than to “add” it after the fact. InDesign allows designers to create beautiful and complex documents, but these features also can create challenges for remediation into a Section 508 compliant PDF.
InDesign offers a direct workflow that reduces the time and effort required to produce accessible,compliant PDF documents from an InDesign layout. Most of the tasks are executed within InDesign, with fewer final steps required in Adobe Acrobat. In addition, this allows hierarchical and structural information to reside in the InDesign file, making updates faster and easier when you need to generate a revised accessible PDF document.
Here’s an Adobe White Paper that can help you design with accessibility in mind.