Standard
WCAG 2.1 Level AA for PDF documents
Which success criteria actually apply to a PDF, how each one is satisfied in the file format, and which ones no tool can check for you.
W3C · technical standard: WCAG 2.1 Level AA
The criteria that actually bite in a PDF
Not all fifty AA criteria are meaningful for a document. These are the ones that decide whether a PDF works.
1.1.1 Non-text Content (A). Every image carries meaning or it does not. Meaningful ones are Figure elements with /Alt; decorative ones are artifacts. An empty /Alt is not the PDF equivalent of alt="" — it is a failure. Figure alt text →
1.3.1 Info and Relationships (A). The largest single bucket. Headings tagged as headings, lists as lists, tables with header associations, form labels connected to fields. Almost every structural Matterhorn condition maps here.
1.3.2 Meaningful Sequence (A). Reading order. The structure tree, not the page layout, defines it. Why tags read out of sequence →
1.4.3 Contrast (AA) and 1.4.11 Non-text Contrast (AA). Nothing to do with tagging, and no PDF tool checks them properly. Measure the design, not the file.
2.4.2 Page Titled (A). A document title in the metadata, plus DisplayDocTitle so the viewer shows it. How →
2.4.3 Focus Order (A). For a form, tab order must follow the structure: /Tabs /S on every page carrying annotations.
2.4.4 Link Purpose (A). Link text that means something out of context, in a Link structure element with a description.
3.1.1 Language of Page (A) and 3.1.2 Language of Parts (AA). /Lang on the catalog, overridden where the language changes. In a Hebrew document this is the difference between usable and unusable. Why →
4.1.2 Name, Role, Value (A). Form fields need an accessible name, which in PDF means /TU. The label printed beside the field is not connected to it. How →
The mapping problem
PDF/UA-1 and WCAG 2.1 are not the same standard and do not map cleanly. Some PDF/UA requirements — the Suspects flag, CIDSystemInfo consistency, reference XObjects — have no WCAG counterpart at all. Some WCAG criteria — contrast, meaningful link text, sensible heading text — have no PDF/UA counterpart.
Taggart records the mapping explicitly in a single shared rule file, so a finding tells you which PDF/UA clause it fails, which WCAG criterion it touches, and where the two do not correspond. That file drives the check engine, the report and this site, so they cannot disagree with each other.
What no tool can decide
Roughly a third of what WCAG asks of a document is judgement:
- whether alt text conveys what the image contributes
- whether the reading order matches the author’s intent, rather than merely being a consistent order
- whether a heading is a heading, or just big text
- whether link text means anything out of context
- whether a table is data or layout
Taggart surfaces every one of these as an explicit decision with the page region highlighted, records what you decided and when, and prints it in the report. That record is not compliance. It is the evidence a person made the call, which is the most any tool can honestly offer.
Frequently asked questions
Does WCAG apply to PDFs at all? It says 'Web Content'.
Yes. WCAG 2.1 is written to apply to content of any technology delivered over the web, and W3C publishes PDF-specific techniques for exactly this. Every legal instrument that regulates documents — ADA Title II, Section 508, EN 301 549, the EAA — points at WCAG for PDFs.
Which level do I need?
Level AA, in every instrument that matters. ADA Title II names WCAG 2.1 Level AA. Section 508 incorporates WCAG 2.0 Level AA. EN 301 549 requires Level AA for non-web documents. Level AAA is not required by any of them.
Can software tell me if I meet WCAG?
For some criteria, yes — a missing document language or an untagged image is decidable. For most of the ones that matter it cannot. Whether alt text is accurate, whether reading order is logical, whether a heading is really a heading: all judgement. Any tool reporting a WCAG percentage is reporting the percentage of what it can check, which is not the same number.
What about WCAG 2.2?
It adds nine success criteria, mostly about input modality and focus appearance, and most have limited bearing on a static document. The instruments currently name 2.1 or 2.0. Meeting 2.1 AA is the practical target today.
Related failure conditions
- 09-001 Tags are not in logical reading order The order of elements in the structure tree does not match the order a human would read the page. This is the single most common substantive defect in tagged PDFs and the one Acrobat's own tooling handles worst.
- 11-001 Natural language for text in page content cannot be determined No /Lang is in effect for some text: neither on the catalog, nor on an enclosing structure element, nor on a marked-content sequence.
- 13-004 Figure tag alternative or replacement text missing A Figure element has neither /Alt nor /ActualText. Every Figure must have one or the other; if the image is decorative it should be an artifact instead of a Figure.
- 14-003 Numbered heading levels in descending sequence are skipped The heading hierarchy jumps a level going down — H1 straight to H3. Going back up any number of levels is fine; going down must be one level at a time.
- 28-005 A form field has neither a TU entry nor an alternative description The /TU tooltip is the accessible name of a PDF form field. Without it the field has no name at all — the visible label printed next to it is not connected to the control.
Check your own file. Taggart's validator is free and unlimited — no page cap, no watermark, no account.
Primary source: https://www.w3.org/TR/WCAG21/. This page is a working summary, not legal advice.
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