Question

How can I use Google Tag Manager’s new readAnalyticsStorage API to solve consent-mode tracking issues?

Answer 1

Google’s readAnalyticsStorage API lets you retrieve GA4’s client ID and session ID inside Google Tag Manager,  but only if the user has granted analytics_storage consent. This removes the need for cookie parsing and makes your tracking privacy-compliant.

Here’s exactly how to use it in practice:

1. Enable Consent Mode in GTM

• Go to Admin > Consent Settings in GTM.

• Enable Consent Mode.

• Set up triggers that fire only when analytics_storage is granted.

2. Create a Custom Template in GTM

• In GTM, go to Templates > New > Tag Template.

• Add the API call:

[javascript]

const ids = await readAnalyticsStorage();

if (ids) {

  const clientId = ids.clientId;

  const sessionId = ids.sessionId;

  // Send to your desired platform

}

• Save and publish the template.

3. Capture IDs When Consent Is Given

• Create a new Tag using your custom template.

• Set the trigger to fire when:

  • Form submissions occur, OR

  • A specific event is tracked (e.g., purchase, lead).

• Make sure your trigger checks for analytics_storage consent.

4. Send IDs to Your Destination

Example: Sending to a CRM

• Add a hidden field in your lead form for the GA client ID.

• When the form is submitted, GTM passes the ID into that hidden field and sends it along with the form data.

Example: Sending to Google Ads for Enhanced Conversions

• Use the Enhanced Conversions tag in GTM.

• Pass the GA client ID as an additional parameter for better matching.

5. Test Your Setup

• Use GTM Preview Mode to ensure the tag only fires when consent is granted.

• Check your GA4 DebugView or your CRM logs to confirm IDs are being sent correctly.

Result: You’ll have reliable, consent-compliant GA4 IDs for attribution and tracking, without breaking privacy laws or relying on fragile JavaScript hacks.