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Untagged PDF: what it means and how to fix it

An untagged PDF looks normal on screen but carries no description of its own structure. Nothing in the file says which line is a heading, where a table starts or what a picture shows. Here is what that means for readers, how to tell, and how to fix it.

Checked against the sources on 28 October 2026.

What tags are

A PDF describes where to draw each letter, line and image on a page. Tags are a separate layer, a structure tree, that describes what those pieces are: heading, paragraph, list, table with header and data cells, figure with alternative text, or decoration to be skipped. The W3C's PDF techniques for WCAG are written for tagged PDF: its techniques for headings and for reading order both state that they apply to tagged PDF documents.

An untagged file has the drawing instructions and nothing else.

What it means for someone using a screen reader

In a tagged file, the reading order is determined primarily by the order of the tags. Without them, the order comes from however the file happens to have been drawn. The W3C gives the typical result: a screen reader may read a two-column page from top to bottom straight across both columns. There are also no heading tags to jump between, no table structure to tie a number to its column header, and no place to put alternative text for an image.

For a one-page notice this is an inconvenience. For a 60-page budget or a set of meeting minutes, it can make the document very hard to use.

How files end up untagged

  • Exported with tagging off. Word on Windows has a "Document structure tags for accessibility" option in the PDF export settings. If it is unchecked, the PDF comes out without tags.
  • Scanned. A scanned page is an image of text. It has no text at all until it is run through optical character recognition (OCR), let alone tags.
  • Made by a tool that does not write tags. Not every program that produces PDFs writes a structure tree.

A related case is the half-tagged file: it declares itself tagged but has an empty structure, or has structure but does not declare it. Checkers report these too, and the fix is the same.

How to tell

Any of the free tools in how to check if a PDF is accessible will say whether a file is tagged: PAC, veraPDF, Acrobat Pro's Accessibility Checker, or the quick check on our home page, which also distinguishes "untagged", "marked as tagged but empty" and "has structure but is not marked as tagged".

How to fix it

1. Go back to the source, if you have it

This fixes the problem where it started. Open the Word file, give it real heading styles and alternative text, and export again with tags on. Microsoft's instructions:

  • Windows: File, Save As (or Save a Copy), choose PDF, select Options, and make sure "Document structure tags for accessibility" is checked.
  • Mac: in the export dialog choose "Best for electronic distribution and accessibility". Microsoft labels this option "uses Microsoft online service", so the file is processed by Microsoft; check that this is acceptable for the document.

Microsoft also recommends running its Accessibility Checker before you export.

2. No source file: tag the PDF

Adobe lists "conversion of untagged PDFs to tagged PDFs from within Acrobat" among Acrobat Pro's accessibility features. Automatic tagging is a starting point, not an end: the W3C notes that complex layouts may not convert in the correct order and need manual repair. Afterwards, look at the reading order, the heading levels, the table header cells and every image's alternative text.

3. Scanned pages: OCR first

Tags cannot describe text that is not there. Run OCR, correct what it misread, then tag. See scanned PDFs and OCR.

4. Check the result, then listen

Run PAC or veraPDF on the repaired file, then open it with a screen reader such as NVDA. A file can carry tags and still have them wrong; only a person can tell whether a heading really is a heading. For many files at once, see how to remediate many PDFs, and for what fixing costs elsewhere, PDF remediation cost.

What tagging does not fix

Tags describe content; they do not change it. Low colour contrast, text that only exists inside an image, and unclear writing remain after tagging, and need changes to the document itself.

Sources

Find out whether your file is tagged

The free quick check reads the PDF in your browser and tells you in plain words; nothing is uploaded. If you have a pile of untagged files and no source documents, Pagorin's Starter plan tags 100 pages a month for US$79, runs veraPDF on each result and lists what still needs a person to confirm.