GA4 Implementation

This skill is the knowledge base behind the ga4-implementation-expert agent. It covers everything needed to deploy Google Analytics 4 with Google Tag Manager on a real website: the legal/compliance layer that is mandatory in the EU, the technical installation across frameworks, the event and conversion taxonomy, the audiences for remarketing, and the diagnostic patterns to figure out why a site is not converting.

Compliance is the blocking prerequisite

GA4 cannot be legally deployed in Italy or the EU without all of the following:

1. A technical Consent Management Platform (CMP) that blocks GA4 cookies before user consent, not just a written cookie policy
2. A cookie banner that meets the Italian Garante requirements (equal-weight Accept/Reject, granular preferences, no scroll-as-consent, 6-month resuppression)
3. Google Consent Mode v2 with all four signals (analytics_storage, ad_storage, ad_user_data, ad_personalization) set to denied by default
4. Accepted Data Processing Terms (Art. 28 GDPR) in the GA4 account settings
5. Google Signals disabled for EEA traffic

A cookie policy page that describes which cookies the site uses does not satisfy the law. The site must have a technical mechanism that prevents the cookies from being set in the first place. This is the most common compliance failure on Italian and EU sites.

For non-EU traffic the legal bar is lower, but Consent Mode v2 is still mandatory by Google policy since 6 March 2024 for any property serving any EEA user. Without it, Google disables remarketing and audience building.

How to use this guide