---
title: Unique id on Active Elements | Accessibility Rule
description: IDs of active elements must be unique
source_url:
  html: https://testingbot.com/support/accessibility/web/rules/duplicate-id-active
  md: https://testingbot.com/support/accessibility/web/rules/duplicate-id-active/index.md
---
# Make sure every id attribute value of active elements is unique

Rule ID: duplicate-id-activeUser Impact: seriousGuidelines: Deprecated

Each `id` attribute in HTML must be unique, especially on **active or focusable elements**. This rule checks for duplicate IDs that can confuse assistive technologies and break client-side scripts.

## What is being tested?

The rule verifies that no two active or focusable elements share the same `id` value. Focusable elements include form controls, links, buttons, and interactive widgets.

## Why it matters

Duplicate IDs can break relationships between `<label>` and form fields, table headers and cells, or ARIA attributes. Screen readers and scripts usually act only on the first element with that ID, ignoring duplicates and causing accessibility failures.

## How to fix the problem

- Ensure every `id` value is unique on the page.
- Rename duplicate `id` attributes to meaningful, distinct names (e.g., `email-input`, `email-input-2`).
- Validate your HTML using tools like the [W3C Markup Validator](https://validator.w3.org/).

## Example code

**Incorrect example:** (duplicate id)

    <input type="text" id="username">
    <input type="text" id="username">

**Correct example:** (unique ids)

    <input type="text" id="username">
    <input type="text" id="username-2">

## Best practices

- Use IDs only when needed (e.g., to link labels, ARIA attributes, or scripts).
- Favor `class` selectors for styling instead of IDs.
- When using JavaScript, target elements by class or data attributes when possible to avoid ID conflicts.

## Important notes

- Duplicate IDs may not break page rendering but can silently break accessibility and JavaScript behavior.
- Assistive technologies may only reference the first instance of a duplicated ID, making other elements invisible to users.

## Other Rules

Interested in other web accessibility rules? Please see these other rules:

- [duplicate-id](https://testingbot.com/support/accessibility/web/rules/duplicate-id)