Complex writing can be appropriate, but only when users are not excluded by it. When text requires advanced reading ability, some users may struggle to understand it even if they can technically read the words.
Users with reading disabilities, cognitive impairments, limited literacy, or who are reading in a second language may find complex sentence structures, long paragraphs, or dense vocabulary difficult to follow. When content becomes hard to read, users need a clearer alternative.
WCAG Success Criterion
3.1.5 Reading Level (Level AAA)
When text requires reading ability more advanced than the lower secondary education level, supplemental content, or a version that does not require reading ability more advanced than the lower secondary education level, is available.
This is a Level AAA success criterion. It is not required for Level A or AA conformance, but it is especially relevant for educational, public-facing, medical, legal, and instructional content.
Intent of the Success Criterion
This criterion intends to ensure that people can understand content even when the original text is complex or specialised. WCAG does not prohibit complex writing. Instead, it requires that users be given help when the complexity exceeds what most people can reasonably read.
This criterion exists to:
- Support users with reading and cognitive disabilities
- Reduce barriers caused by dense or technical language
- Allow authors to publish advanced material without excluding readers
What “Lower Secondary Education Level” Means
Lower secondary education roughly corresponds to 7–9 years of schooling (around middle school level). This does not mean content must always be written at that level.
It means:
- If the text exceeds that level, users must be given a simpler alternative
- Proper names and titles are ignored when assessing difficulty
- Each language on a multilingual page is evaluated separately
WCAG does not require a specific readability formula, but tools such as Flesch-Kincaid, SMOG, or language-specific equivalents may be used to estimate reading level.
What This Criterion Requires
If your content is hard to read, you must provide help.
That help may include:
- A simplified summary
- A plain-language version
- Supplemental explanations
- Visual or audio alternatives that reduce reading demand
Supplemental content must convey the same essential information as the original text.
A simplified version cannot omit requirements, instructions, risks, or consequences that users need in order to understand or act on the content.
WCAG does not require automatic simplification. It requires that users have access to a version of the content that does not demand advanced reading ability.
What Does Not Count as Meeting This Criterion
- Assuming “the audience is educated enough”
- Reducing font size, spacing, or layout instead of simplifying language
- Relying only on context or examples to explain complex text
- Providing definitions for individual words while keeping the overall structure complex
- Expecting assistive technologies to “make it simpler”
Reading level is about language complexity, not presentation.
WCAG Exceptions and Important Clarifications
WCAG allows certain complexity to remain when simplifying it would change the meaning.
This includes:
- Proper names
- Titles of works
- Unavoidable technical or legal terms
The requirement is to support understanding, not to remove necessary precision.
Realistic Examples
Passing Example: Scientific Content
A research article is written for specialists, but includes a clearly labeled plain-language summary explaining the findings in simpler terms.
Passing Example: Medical Information
A health website presents treatment information in simplified language for the public, with optional links to detailed clinical explanations.
Failing Example
A government service page uses long sentences, legal terms, and dense paragraphs, with no summaries or simplified explanations.
Relationship to Other Criteria
- 3.1.3 Unusual Words — defines jargon and idioms
- 3.1.4 Abbreviations — expands shortened forms
- 3.1.1 Language of Page — identifies the language
- 3.1.2 Language of Parts — marks language changes
Reading Level focuses on overall comprehension, not individual words.
How to Test
- Identify long or complex sections of text
- Ask: Would this be difficult for a general audience to understand?
- Evaluate whether a simpler version or summary is available
- Confirm that the simplified content conveys the same essential meaning
- Ensure users can easily find the simpler version without searching or prior knowledge
If users must struggle through complex text with no alternative, the criterion is not met.
Benefits
This success criterion benefits people who:
- Have reading or learning disabilities (e.g. dyslexia)
- Use braille or screen readers for long-form content
- Read in a second language
- Experience cognitive fatigue from dense text
Clear alternatives reduce mental effort and improve comprehension.
Wrapping Up
WCAG 3.1.5 does not ban complex writing. It acknowledges that complexity can be necessary, but not exclusive. By offering simplified alternatives when text becomes difficult, authors remove a major barrier to understanding. While this is a Level AAA requirement, applying it makes content understandable to users who would otherwise be excluded.
