Key Takeaways
- Principle: Once Tag Manager is installed on the site, it loads GA4 and all other tags without requiring any further technical intervention.
- Minimum system requirements: A Google tag (ID: G-XXXX) triggered on all pages, plus "GA4 event" tags for key actions: form submissions, phone clicks, downloads, and purchases.
- Required in 2026: Consent Mode v2, linked to the cookie banner; otherwise, GA4 loses data and Google Ads can no longer model conversions.
- Check: Check the Tag Manager overview and GA4 DebugView before each release; a conversion reported without testing is incorrect half the time.
Google Analytics 4 can be installed in two ways: by pasting the code directly into the website, or by using Google Tag Manager. The second approach has become the standard because it allows you to add events, conversions, and other tools without having to modify the code each time. Here’s how to link the two, in order, using settings that prevent the most common measurement errors.
Why use Tag Manager instead of code?
| Criterion | GA4 in the website code | GA4 via Tag Manager |
|---|---|---|
| Initial Setup | A snippet to paste, or a CMS extension | A container you paste once, and then everything is done through the interface |
| Add an event | Development Every Time | Tag and trigger created in just a few minutes |
| Other Tools (Ads, Meta, LinkedIn) | One excerpt per tool, scattered throughout the site | All managed in one place |
| Consent | To be coded for each tag | Centrally managed via consent mode |
| Pre-launch testing | Difficult | Built-in preview mode, versions, and undo |
| Risk | Little risk of breakage | A tag that triggers incorrectly doubles the number of page views; testing is essential |
The CMS extension or “site builder” installation offered by GA4 is suitable for a website that will only ever track page views. As soon as there’s a form or a phone number to track, Tag Manager saves you time.
Step 1: The Google tag on all pages
- Create a web container in Tag Manager and paste its two snippets into the website (in the header and at the beginning of the page body), or via the CMS extension.
- In GA4, note the web stream measurement ID (format: G-XXXXXXX).
- In Tag Manager, create a "Google Tag" tag, enter the ID, and set it to fire on "Initialization: All Pages."
- Publish, then check in real time in GA4 to see if a session appears.
Since 2023, this Google tag has replaced the old “GA4 configuration.” It also carries shared settings (pageview tracking, consent settings) and can feed data into Google Ads using the same ID. Do not duplicate the installation: if the GA4 code is already present in the theme or a plugin, remove it; otherwise, each page view will be counted twice. The property-level settings are detailed in Set up GA4 correctly from the start.
Step 2: Events That Matter to the Company
GA4 automatically tracks page views, 90% scroll depth, outbound clicks, file downloads, and embedded YouTube video views, provided that enhanced measurement is enabled in the stream. Everything else is handled via “GA4 Event” tags in Tag Manager. For an SMB, the list of useful tags can be summarized in just a few lines:
| Action | Tag Manager Trigger | Recommended Event Name | Conversion |
|---|---|---|---|
| Submitting a contact form | Form submission, thank-you page, or visible "thank you" message | generate_lead | Yes |
| Click on a phone number | Click on the link that starts with "tel": | click_phone | Yes |
| Click on an email address | Click on the "mailto:" link: | click_email | By Activity |
| Schedule an appointment, get an online quote | Confirmation page or module event | book_appointment, request_quote | Yes |
| Purchase (e-commerce) | "purchase" event pushed to the dataLayer by the store | purchase, with amount and currency | Yes |
| Add to Cart | "add_to_cart" event in the dataLayer | add_to_cart | No |
Use the names recommended by Google when available (generate_lead, purchase, sign_up): GA4 and Google Ads recognize them, and the reports make better use of them. Event types and their parameters are explained in Definition and Types of GA4 Events. Once the event has been received in GA4, you must mark it as a key event for it to count as a conversion; the procedure is in Enable conversion tracking in GA4.
Step 3: Consent-based mode—non-negotiable in 2026
Since March 2024, Google has required Consent Mode v2 for any use of audiences and conversion tracking within the European Economic Area. Specifically:
- The cookie banner (Axeptio, Tarteaucitron, Cookiebot, Didomi, etc.) must send consent statuses—including analytics_storage and ad_storage—to Tag Manager.
- Tag Manager sets the default status to “rejected” before any selection is made, then updates it after the user clicks; most banners provide a ready-to-use Tag Manager template.
- The Google tag and event tags automatically comply with these settings: without consent, GA4 does not set any cookies and sends only anonymous signals (or none at all, depending on the selected mode).
The French framework adds its own requirements, as outlined in GA4 and the GDPR : prior consent, clear information, retention period. A website that loads GA4 before obtaining consent risks receiving a formal notice, and a website that does not report data correctly loses conversion tracking in Google Ads.
Step 4: Test Before Publishing
- Enable Tag Manager's preview mode (Tag Assistant), browse the site, and verify that each tag fires at the right time—and only once.
- Open GA4's DebugView: the events should appear there with their parameters, in the expected order.
- Testing the opt-out: No GA cookies should be set, and no complete events should be sent.
- Publish with a version description; if in doubt, revert to the previous version with a single click.
- Check 48 hours later to see if the events appear in the reports, and then mark them as key events.
The Most Common Mistakes
- Dual installation: CMS extension plus Tag Manager, or two Google tags; symptoms include an abnormal engagement rate and a doubling of page views.
- Trigger too wide: A `generate_lead` event triggered whenever a form is submitted, including internal searches or newsletter sign-ups.
- Event with no parameters: A purchase with no value or currency renders the revenue reports unusable.
- Consent Gone Wrong: A default setting that has never been updated, or a banner that doesn't communicate with Tag Manager; symptoms include a 30–50% drop in data or, conversely, data collection before consent is obtained.
- Test environment included: forget to filter internal traffic and pre-production traffic.
Once the measurement is reliable, the results can be viewed in GA4 or in a reporting tool that integrates GA4 with Search Console and Google Ads; what a GA4 event A solid foundation directly determines the quality of everything that follows.
How GreenRed Can Help You
Instead of juggling multiple tools, GreenRed's GA4 Performance and Traffic Module brings these metrics together in a single dashboard, compares them over time, and shows you which actions to prioritize. You can try it for free—no credit card required—from the page Rates.
Frequently Asked Questions
Can GA4 be installed without Google Tag Manager?
Yes, by pasting the gtag.js snippet into the website or using the CMS extension. That’s all it takes to track page views. However, when you need to track a form submission, a phone call, or a purchase along with its value, Tag Manager eliminates the need for custom development each time you add a new element and allows you to test changes before publishing. For a professional website, it quickly becomes indispensable.
What is the difference between the Google tag and the GA4 event tag?
The Google tag loads GA4 on every page with the measurement ID and common settings; it sends the page view. "GA4 Event" tags rely on it to send specific actions—such as form submissions, clicks, and purchases—along with their parameters. You need only one Google tag per property, and as many event tags as there are actions to track.
Is consent mode mandatory for GA4 in France?
Prior consent is required in France to set GA4 cookies, regardless of Google. The Consent v2 mode, on the other hand, has been required by Google since March 2024 to use audiences and conversion tracking in Google Ads in Europe. The two go hand in hand: the banner collects the user’s choice, and Tag Manager transmits it to the tags.
How can I verify that GA4 is receiving events correctly?
Use Tag Manager's preview mode to see the tags fire, then use GA4's DebugView, which displays each received event and its parameters in real time. The real-time report confirms overall receipt. Standard reports don’t display new events until 24 to 48 hours later; don’t assume there’s a failure before that time has elapsed.