Implement Google Consent Mode v2
Adjust Google Tag behavior based on user consent to comply with privacy regulations and maintain data insights.
- Adjust tag behavior based on user consent for privacy compliance
- Maintain data insights through modeling for non-consenting users
- Ensure the `gcd` parameter is present in pings to Google services
Rule Details
Google Consent Mode v2 is a mechanism that allows you to communicate your users' cookie or app identifier consent status to Google. Tags will adjust their behavior and respect users' choices.
Code Examples
Setting Default Consent (gtag.js)
This should be placed as high as possible in the <head>, before any GTM or gtag.js scripts.
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
// Default all to denied
gtag('consent', 'default', {
'ad_storage': 'denied',
'ad_user_data': 'denied',
'ad_personalization': 'denied',
'analytics_storage': 'denied',
'wait_for_update': 500
});
</script>Updating Consent after User Action
When a user accepts cookies via your CMP (Consent Management Platform):
function onConsentAccepted() {
gtag('consent', 'update', {
'ad_storage': 'granted',
'ad_user_data': 'granted',
'ad_personalization': 'granted',
'analytics_storage': 'granted'
});
}Why It Matters
- Regulatory Compliance: Required for businesses operating in the European Economic Area (EEA) to comply with the Digital Markets Act (DMA).
- Data Modeling: When users don't consent, Consent Mode uses conversion modeling to fill in the gaps, providing a more complete view of performance.
- Privacy First: Respects user choices by ensuring that advertising and analytics cookies are only used when explicit consent is granted.
- Functional Continuity: Allows basic measurement to continue even without personal data collection.
Best Practices
Validate the implementation with Google Tag Assistant (opens in new tab) so you can confirm the consent state actually changes the requests sent after a user decision, not just the values stored in the page.
✅ Use a Certified CMP: Use a Consent Management Platform that is certified by Google to ensure correct implementation.
✅ Default to Denied: For users in the EEA, default consent states should be set to 'denied' until the user provides explicit consent.
✅ Update Promptly: Ensure the consent update is sent immediately after the user interacts with the consent banner.
✅ Verify with Tag Assistant: Use Google Tag Assistant to inspect pings and ensure the gcd and gcs parameters are correct.
❌ Don't Hardcode 'Granted': Never set consent to 'granted' by default for users in regulated regions.
❌ Don't Delay GTM Loading unnecessarily: Use the wait_for_update parameter instead of delaying the entire GTM script load.
Tools & Validation
- Google Tag Assistant (opens in new tab): Debugging tool to verify consent signals.
- Chrome DevTools: Inspect network pings to
google-analytics.comfor thegcsandgcdparameters. - Tag Manager Debug Mode (opens in new tab): View consent state changes in real-time.
Standards
- Use web.dev: Learn Performance as the standard for measuring the final production behavior, not just local synthetic output.
- Use Chrome Developers: Lighthouse overview as the standard for measuring the final production behavior, not just local synthetic output.
Verification
Automated Checks
- Measure the affected page or flow in Lighthouse, PageSpeed Insights, or DevTools and confirm the targeted metric improves.
- Inspect the network waterfall or performance timeline to confirm the intended resource or execution change actually took effect.
Manual Checks
- Verify the change on a throttled mobile profile, not just local desktop.
- If this rule maps to a budget or Web Vital, confirm the page now stays within that threshold.
Use with AI
Copy these prompts to use with your AI assistant, or install the MCP server to use directly from Claude, Cursor, or Windsurf.
Check
Verify implementation
Verify that Google Consent Mode v2 is correctly implemented and sending the appropriate consent states.
Fix
Auto-fix issues
Update your GTM or gtag.js implementation to support the new `ad_user_data` and `ad_personalization` consent types.
Explain
Learn more
Explain the transition to Consent Mode v2 and why it's required for digital advertising in certain regions.
Review
Code review
Review the routes, assets, and loading behavior that affect Implement Google Consent Mode v2. Flag exact files, requests, or rendering steps that add unnecessary network, CPU, or layout cost, and describe the measurement method used to confirm the issue.