How to fix reading order and headings in a PDF

What goes wrong, and why it matters

A screen reader reads a PDF in the order of its tags, not the order your eyes follow. When that order is wrong, a listener hears a sidebar in the middle of a sentence, a footer before the main text, or a table caption after the table.

Headings cause the other common problem. Screen reader users often jump from heading to heading to scan a document. If a section title is tagged as ordinary text, or a Heading 3 sits where a Heading 2 belongs, the outline stops making sense.

Both problems are easiest to fix in the source file. If you only have the PDF, you can still repair it in Acrobat Pro.

How to spot the problem

Before changing anything, find out what is actually wrong.

1. Listen to it. W3C's technique for reading order (PDF3) recommends listening with a screen reader or read-aloud tool to confirm the order. NVDA is a free screen reader for Windows; Mac and iPhone include VoiceOver.

2. Look at the heading list. Most screen readers can list all headings. Do they form a sensible outline?

3. Open the Tags panel in Acrobat Pro. The tag tree shows each element in reading order. You can expand it to see headings (H1, H2 and so on), paragraphs (P), lists, tables and figures.

4. Run the Accessibility Checker. It typically lists reading order as an item that needs a manual check, which is a reminder rather than a diagnosis.

Fix it at the source (the better route)

If you have the original Word file, fix it there and export again. The repair lasts, and the next version of the document starts clean.

Use built-in heading styles

Microsoft's accessibility guidance says to use the built-in heading styles and to "organize headings in the prescribed logical order and do not skip heading levels." In practice:

• Use the Title style for the document title, or Heading 1 if your organization prefers.

• Use Heading 1 for main sections, Heading 2 for subsections under them, and so on.

• Don't make text look like a heading with bold and a bigger font. To a screen reader it is just a paragraph.

• Don't pick a heading level for its size. Change how the style looks instead.

W3C's heading technique for PDFs (PDF9) describes the same approach: apply heading styles in Word, keep the levels in order, then convert to PDF so the heading tags carry over.

Keep the layout simple to read in order

Reading order problems often come from objects that float outside the main text flow:

• Text boxes and shapes holding important text (a deadline, a phone number).

• Sidebars and pull quotes placed next to the body text.

• Tables built with tabs or spaces instead of a real table.

• Important details in the header or footer. Microsoft notes that screen readers don't scan headers and footers in Word.

Where you can, put content inline in the main text, in the order it should be read. Use columns from the page layout settings rather than separate text boxes.

Export with tags

Microsoft's steps: go to File, Save As (or Save a Copy), choose PDF, select Options, and make sure Document structure tags for accessibility is ticked. Run Word's Accessibility Checker first. A "print to PDF" route usually drops the tags.

Fix it in the PDF with Acrobat Pro

Sometimes there is no source file: an old report, a file from a supplier, a scan. Adobe says you need Acrobat Pro to create and fix accessible PDFs. Menu names shift between versions, so look for the Accessibility tools.

Fix the order in the Tags panel

W3C's technique PDF3 gives the core method: use the Tags panel and either drag and drop a tag to its required position, or cut a tag and paste it where it belongs.

1. Open the Tags panel and expand the tag tree.

2. Click a tag to highlight its content on the page, so you can see what it is.

3. Drag it (or cut and paste it) into the right spot.

4. Listen again with a read-aloud tool.

Fix heading levels with the Reading Order tool

W3C's technique PDF9 walks through correcting a heading that is tagged H3 but should be H2:

1. Open the Accessibility tools and select Reading Order.

2. Open the Tags panel to see the tag tree.

3. Click the text of the wrong heading on the page.

4. In the reading order panel, click the correct heading button, such as Heading 2.

The same tool can retag a block as plain text, a figure or a table, or mark it as background so screen readers skip it.

Check tab order too

For forms and documents with links, W3C's PDF3 also covers tab order. In Acrobat's page properties, the Use Document Structure option makes the Tab key follow the tag order.

A sample repair

Here is a fictional example. The Northgate Community College "Fees and deadlines" PDF has three problems:

• The title is tagged as a paragraph.

• "Payment options" is tagged H3 directly under the title, skipping H2.

• A sidebar with the refund deadline is read after the footer.

The fix takes about ten minutes in Acrobat: retag the title as H1, change "Payment options" to H2, and drag the sidebar tag to sit after the paragraph it relates to. A listen-through confirms the order. The college also fixes the Word original so next year's version starts right.

When to stop and rebuild

Manual tag repair is reasonable for a few pages. For a long, complex layout with dozens of floating elements, rebuilding the source file or converting the content to a web page can be quicker and more reliable.

Hand off the tedious part

EasyToDecode is launching soon with a tool that will tag an existing PDF with headings, reading order and table structure, draft alt text for review, and report what still needs a person to confirm. It does not certify compliance. See how it works or join the waitlist.