Most teams discover a GA4 problem the same way: the dashboard says one thing, the CRM or the ad platform says another, and nobody is sure which number to trust. GA4 will never match a backend system exactly, but a gap of more than a few percent usually points to a fixable setup issue. Here is the checklist we run first.
Why GA4 numbers drift
GA4 counts what the browser lets it count. Ad blockers, declined consent, tags that fire twice, missing cross-domain settings and internal traffic all push the numbers away from reality, in both directions. The goal is not a perfect match; it is a gap you understand and can explain.
The 10-point checklist
- One tag, loaded once. Check the page source and Tag Assistant for duplicate GA4 configs (for example a plugin snippet plus GTM). Doubled page views and sessions are the classic symptom.
- Consent Mode is wired correctly. Default states should be set before any tag fires, and updated when the visitor chooses. Without this, you either lose data or collect it without permission.
- Key events fire exactly once. Thank-you pages that can be refreshed, or form listeners that fire on both click and submit, inflate conversions.
- Internal traffic is filtered. Define your office and team IPs as internal traffic and activate the filter, not just create it.
- Unwanted referrals are listed. Payment gateways and login providers should not appear as traffic sources that steal credit from your campaigns.
- Cross-domain measurement covers every domain in the journey, such as a booking engine or checkout on a separate domain.
- UTM tagging is consistent. Mixed casing (Facebook vs facebook) and missing mediums fragment your channel reports.
- Data retention is set to 14 months, otherwise exploration reports lose history after two months.
- Google Ads and Search Console are linked, so cost and query data sit next to behaviour.
- Revenue and lead values are passed where they exist, with the currency parameter set, so reports show value and not just counts.
Quick fixes vs a full audit
Items 4, 5, 8 and 9 are settings you can change in an afternoon. Duplicate tags, consent wiring and event logic usually need someone to trace them through GTM and the site code. If more than two items fail, a structured audit is faster than fixing things one complaint at a time.
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