GA4 key events from GTM and the Google Ads import path

#01Key events in GA4

According to Google’s measurement docs, you send the event (often via a GA4 Event tag in GTM), then in Google Analytics Admin → Key events you add the event name. That tells GA4 which events matter for reports, attribution views and exports.

Steps:

1. Confirm the event appears in DebugView with the exact name you will mark.
2. GA4 Admin → Key events → New key event → type the exact name (generate_lead).
3. Wait for reporting to populate; use Realtime/Debug for immediate confidence.
4. Optionally configure counting method (once per event vs once per session) based on the action — a lead form should usually count once per submission event, but understand your product’s semantics.

See also GA4 key events setup.

#02Importing key events into Google Ads

Google Ads can use GA4 key events as conversion actions after the accounts are linked. The Ads track covers linking and import details in Using GA4 key events in Google Ads. The GTM-relevant points:

• The event must fire with a stable name from your container.
• Consent Mode and EEA traffic rules still apply (Consent Mode for Google Ads).
• If you also deploy a Google Ads Conversion Tracking tag for the same button, Ads may see two conversions.

Our view: for web lead gen SaaS, many teams prefer GA4 as the source of truth and import key events into Ads, keeping GTM focused on GA4 Event tags plus a Conversion Linker. Other teams prefer native Ads tags for bidding latency reasons. Pick one primary path per action and document it.

#03Conversion Linker still matters

Even when conversions are imported from GA4, Google’s Conversion Linker tag helps store click data in first-party cookies. Google Tag Manager Help recommends deploying Conversion Linker on landing pages. Add it on All Pages in the web container (lesson 9 walks through Ads tags). Do not skip Linker because you "only import from GA4".

#04Primary vs secondary in Ads

In Google Ads, conversion actions can be primary (used for bidding) or secondary (observation). If you temporarily keep both an imported key event and a legacy Ads tag, set one to secondary so Smart Bidding does not optimise on doubles. Details and goal strategy sit in conversion goals.

#05Quality checks before you bid

Never expect perfect equality. Consent denial, ad blockers, multi-step forms and attribution windows create gaps. Directional alignment plus investigation of large deltas is the goal.

#06Worked example: Ledgerline bidding cutover

Ledgerline is a fictional accounts-payable software company. Details are illustrative.

Ledgerline had a legacy Ads conversion tag on the thank-you page and a new generate_lead key event from the HubSpot success push. For two weeks both were primary. CPA looked amazing (double credit) while CRM pipeline did not. They set the thank-you tag to secondary, then removed it after a week of matching counts, keeping the GA4 import as primary.

Competitor B in their market allegedly chased vanishing thank-you page conversions after a CMS redirect change; Ledgerline’s data layer event never cared about the slug.

Walkthrough

1. Mark generate_lead as a key event.
2. Confirm Google Ads link in GA4 Admin.
3. In Ads, import the key event; set goal category (Submit lead form).
4. Ensure Conversion Linker fires on All Pages via GTM.
5. Pause or demote any duplicate Ads conversion tag for the same action.
6. Run five known test conversions with a click ID where possible; confirm Ads shows them under the right action (test prefixes help).

#07Counting methods and SaaS realities

A user who submits three demo forms in one session may be three leads or one intent. Align with Sales:

• Count every successful submit if each is a routing event.
• Count once per session if the CRM merges duplicates aggressively and bidding should too.

Document the choice next to the key event name. Changing counting methods later rewrites how people read trends.

#08Import lag and learning

After importing a new key event into Google Ads as primary, expect a learning period for Smart Bidding. Do not toggle primary/secondary daily. Coordinate with media buyers (Smart Bidding lesson).

#09Offline and hybrid conversions

Some Ledgerline-like motions qualify leads offline. Website generate_lead may be a micro-conversion while final pipeline sits in CRM uploads via Enhanced Conversions for leads / Data Manager (Ads enhanced conversions lesson). GTM still owns the reliable web micro-conversion; offline is a parallel track.

#10Key events vs enhanced measurement events

Enhanced measurement can mark some automatic events as key events (for example file_download). That is rarely the best primary conversion for B2B SaaS. Keep key events tied to revenue semantics. Use automatic events for UX analysis.

#11Multi-conversion funnels

You might mark generate_lead and sign_up as key events and import both to Ads with different goals — one observation, one primary — depending on the funnel. Document which action Smart Bidding should optimise toward. Changing it every week destroys learning (conversion goals lesson).

#12When GTM is correct but Ads import is empty

Check: property link, correct Google account permissions, event name spelling, whether the action was marked as key event, and whether you are filtering test device traffic out of Ads. GTM Preview success does not bypass Ads configuration.

#13Naming key events for humans

Use the same name as the GA4 event (generate_lead), not a poetic Ads label that nobody can grep. If Ads needs a friendlier UI name, change the conversion action name in Ads — keep the underlying event string stable.

#14Session key event rate as a health metric

Track key event rate (sessions with the key event / sessions) weekly for the primary conversion. Sudden drops usually mean: broken trigger, consent regression, SPA change, or a thank-you URL change — not a mysterious demand collapse. Pair with Realtime and a synthetic test before you rewrite creative strategy.

#15Secondary key events

Mark micro-conversions (for example start_trial start, not finish) as key events only when someone will use them for bidding or executive reporting. Otherwise leave them as ordinary events. Too many key events dilute attention in the GA4 UI and invite accidental Ads imports.

#16Try it yourself

Pick one action. Draw the path from user success → data layer → GA4 Event tag → key event → Ads conversion action. Delete or demote anything that creates a second primary path.

#17Quick quiz

1. Where do you mark a key event?

Answer: In GA4 Admin → Key events, using the exact event name.

2. Why is double primary conversion bad?

Answer: Bidding and reporting treat two credits as two successes, distorting CPA and optimisation.

3. Does GA4 import remove the need for Conversion Linker?

Answer: No. Still deploy Conversion Linker for click data storage as Google recommends.

#18What should you check before the next lesson?

• Key event marked for your primary action.
• Ads import path documented.
• No duplicate primary conversions.

Previous: GA4 event tags in GTM. Next: Google Ads conversion tags. Or return to the GTM for Marketers track.

#19Common questions

Key event vs conversion? Key event is GA4’s label; Ads conversions can be imports or native tags.

Import and Ads tag together? Often double-counts if both primary.

When does Ads see imports? After linking/import; still needs real eligible traffic.