- 1 Set default consent to denied
- 2 Banner collects the visitor's choice
- 3 Update the four consent signals
- 4 Tags adapt to granted or denied
- 5 Verify both paths in testing
If you advertise to visitors in regions with consent laws, such as the European Economic Area, Google expects your tags to know what each visitor agreed to. Consent Mode v2 is how you pass that choice to Google tags. Set it up badly and you either track people who said no, or you lose most of your conversion data and remarketing audiences. Set it up well and you stay compliant while keeping as much measurement as the visitor’s choice allows.
Why it works
Consent mode separates two questions: may this tag store cookies, and may this data be used for advertising? Each tag reads four signals, ad_storage, analytics_storage, ad_user_data and ad_personalization, and adjusts what it does. When consent is denied, Google tags stop using cookies, and in advanced mode they still send cookieless signals that let Google model the conversions it can no longer observe directly.
That is the trade. Instead of an all-or-nothing choice between ignoring consent and switching tracking off, you get compliant behaviour plus modelled data that keeps bidding and reporting usable.
How to do it
- Map who needs it. Check which of your visitors come from regions where consent is required, and which Google products you use: GA4, Google Ads conversions, remarketing.
- Choose a consent tool. A consent management platform (CMP) that integrates with consent mode saves a lot of work. If you build your own banner, you will call the consent API directly.
- Set defaults before any tag fires. The default consent state, usually
deniedfor all four signals in regions that require consent, must load before Google tags. In a tag manager, that means a consent initialisation trigger, not a normal page-view trigger. - Update on the visitor’s choice. When someone accepts or rejects, the banner must send a consent update with the right value for each signal. Accepting analytics only should not grant the advertising signals.
- Decide basic or advanced mode. Basic blocks Google tags until consent; advanced loads them in a restricted, cookieless state. Get legal input; the decision depends on your jurisdiction and risk tolerance.
- Test every path. In a clean browser, test accept-all, reject-all and partial choices. Confirm the default fires first, the update follows the click, and no advertising cookies appear after a rejection.
- Check it in Google’s own tools. Tag Assistant shows the consent state each tag saw, and Google Ads shows consent mode status for your conversion actions.
Example
Say a B2B SaaS company runs Google Ads across Europe. Its banner blocks all tags until consent, with no consent mode, so most European conversions simply disappear and remarketing lists shrink. The team switches to a CMP with consent mode support, sets all four signals to denied by default, maps the banner’s “marketing” choice to ad_storage, ad_user_data and ad_personalization, and maps “analytics” to analytics_storage. After testing each path, Google Ads begins reporting modelled conversions for visitors who declined, and bidding stops starving on missing data.
Metrics to track
- Consent rate by region and by device: the share of visitors who accept each category.
- Share of conversions that are modelled in Google Ads, if you use advanced mode.
- Conversion volume before and after setup on a consistent date range, to confirm you did not lose data you are entitled to.
- Tag errors in testing, such as tags firing before the default consent state loads.
When it backfires
- Defaults load too late. If tags fire before the default consent command, the first hit of every visit may ignore the visitor’s rights. This is the most common implementation mistake.
- Mis-mapped categories. Granting all four signals when the visitor only accepted analytics breaks the visitor’s choice and your compliance.
- Treating it as legal sign-off. Consent mode is a technical mechanism. Whether your banner and data use are lawful is a separate question for legal advice.
- Never re-testing. Banner updates, new tags and tag manager edits can silently break the order of consent commands. Re-test after each change.
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Questions people ask
What changed in Consent Mode v2?
Version 2 added two signals, ad_user_data and ad_personalization, alongside the original ad_storage and analytics_storage. They tell Google whether user data may be sent for advertising and whether it may be used for personalised ads.
What is the difference between basic and advanced consent mode?
In basic mode, Google tags do not load at all until the visitor consents. In advanced mode, tags load with consent denied and send cookieless signals, which Google can use for conversion modelling. Which one is right depends on your legal advice and risk appetite.
Do I need a cookie banner tool to use consent mode?
You need something that collects consent and updates the consent signals. Many consent management platforms do this for you; Google lists certified partners. You can also implement it yourself with the consent API.