IDs used in ARIA and labels must be unique

Rule ID: duplicate-id-aria
Ruleset: axe-core 4.3
User Impact: Critical
WCAG: 4.1.1

Compliance Data & Impact

User Impact

Critical
Minor
Critical

Disabilities Affected

  • Blind
  • Deafblind

Requirement(s)

  • WCAG 2.0 (A): MUST

WCAG Success Criteria

  • 4.1.1 Parsing

Section 508 Guidelines

  • Not specified, or not applicable

How to Fix the Problem

Rename any duplicate ID values.

Duplicate IDs are common validation errors that may break the accessibility of labels, e.g., form fields, table header cells.

To fix the problem, change an ID value if it is used more than once to be sure each is unique. Unique ID's differentiate each element from another and prevent invalid markup, wherein only the first instance gets acted upon by client-side scripting, or where assistive technologies typically only reference the first one accurately.

Why it Matters

Duplicate IDs are common validation errors that may break the accessibility of labels, e.g., ARIA elements, form fields, table header cells.

Unique ID's differentiate each element from another and prevent invalid markup, wherein only the first instance gets acted upon by client-side scripting, or where assistive technologies typically only reference the first one accurately.

Rule Description

The value assigned to an id attribute used in ARIA or in form labels must be unique to prevent the second instance from being overlooked by assistive technology. Put another way; ID values used in ARIA and in labels may not be used more than once in the same document to differentiate each element from another.

The Algorithm (in simple terms)

Ensures every ID used in ARIA attributes and for attribute on a label is unique

Resources

Other Resources

You may also want to check out these other resources.

Refer to the complete list of axe 4.3 rules.

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