Section 508 of the Rehabilitation Act applies to U.S. federal agencies and any company selling tech to the federal government. Its current technical standard incorporates WCAG 2.0 Level AA — which makes alt text mandatory on every non-decorative image. Selling to GSA, DHA, VA, or any cabinet department without 508 compliance isn't viable.

This guide covers what 508 actually requires for images, what a VPAT looks like, and how to make 508 conformance a non-issue for your product.

Key Takeaways

• Section 508 incorporates WCAG 2.0 AA (some agencies are moving to 2.1 AA).
• WCAG SC 1.1.1 (alt text on non-text content) is required at every conformance level.
• Every product sold to the U.S. federal government typically requires a VPAT — a Voluntary Product Accessibility Template — documenting WCAG conformance.
• Missing or inadequate alt text is the most-flagged issue in federal accessibility reviews.

What Is Section 508?

Section 508 of the Rehabilitation Act of 1973 (significantly amended in 2018) requires federal agencies to make their electronic and information technology accessible to people with disabilities. The 2018 "508 Refresh" updated the standards to incorporate WCAG 2.0 AA — meaning the federal accessibility standard is now defined by reference to WCAG.

The U.S. Access Board maintains the standard at access-board.gov/ict. The standard applies to:

• Federal agency websites and apps
• Software, hardware, and IT services procured by the federal government
• Documents (PDFs, presentations) shared with the public
• Multimedia and digital signage

Alt Text Requirements Under 508

Because 508 incorporates WCAG 2.0 AA, the alt text requirements are exactly WCAG SC 1.1.1: text alternatives for all non-text content, sufficient to convey equivalent meaning. The same six sub-categories apply — controls/inputs, time-based media, test content, sensory experience, CAPTCHA, decorative.

For full coverage of what 1.1.1 requires, see the WCAG Alt Text Guide.

VPATs and Conformance Reports

Selling tech to the federal government almost always requires a VPAT — Voluntary Product Accessibility Template. The VPAT is a document where you self-report conformance to each WCAG criterion. For SC 1.1.1, you mark "Supports," "Partially Supports," or "Does Not Support," and you write a remarks column explaining how.

Federal procurement officers read VPATs to decide whether to buy. A VPAT that says "Does Not Support" on 1.1.1 is a near-instant disqualification for most contracts.

The current template format is VPAT 2.5 (released by ITI, the trade association). Companies often hire third-party accessibility firms to validate their VPAT before submitting.

The Trusted Tester Program

For federal agencies, the DHS-led Trusted Tester program trains accessibility testers in standardized methodology. Their checks include automated scans (axe, WAVE) plus manual review for context-appropriate alt text. Sites that pass automated scans but fail manual review (filename-as-alt, generic alt, redundant alt) routinely fail Trusted Tester audits.

How to Comply

For federal agencies

1. Inventory every web property and IT system the agency operates.
2. Run automated scans (axe, Pa11y, WAVE) to identify missing alt text.
3. Triage decorative vs informative; remediate.
4. Establish ongoing CI checks that block merges when alt text regresses.

For federal contractors

1. Maintain a current VPAT for your product.
2. Make sure every UI image, marketing image, and documentation image has appropriate alt text.
3. Build alt text generation into your content pipeline so new content ships compliant by default.
4. Schedule annual third-party accessibility audits to keep the VPAT honest.

Alt Text in PDFs and Documents

Section 508 covers documents, not just web pages. PDFs sold or shared with the federal government need:

• Tagged structure (proper heading hierarchy)
• Alt text on every image inside the PDF
• Reading order that makes sense when read by a screen reader

Adobe Acrobat Pro can add alt text to PDF images via the Tags panel. For high-volume document workflows, automated alt text generation tools that work on document images (not just web images) save substantial manual effort.

Related

• WCAG Alt Text Guide (2026)
• ADA Compliance for Images (2026)
• Screen Reader Alt Text
• What Is Alt Text?