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How to Set Up and Verify Consent Mode v2 in Google Tag Manager

Consent Mode v2 is a technical mechanism for telling Google tags what a visitor has agreed to, and for adjusting tag behaviour accordingly. This guide covers implementing it in Google Tag Manager and, more importantly, verifying that it does what you think. One thing first, stated plainly because a great deal of South African marketing content is vague about it. POPIA contains no cookie-specific provision equivalent to the EU ePrivacy rule that drives European consent banners. Obligations around tracking in South Africa flow from the general processing provisions of the Act, and how they apply to cookies on your specific site is a legal question for your own counsel, not a question this guide answers. We are not lawyers and this is not legal advice. What we can say is the technical case: Consent Mode v2 is how you keep Google tags behaving predictably when a visitor declines, and if you serve any EU traffic at all you will need it regardless of the domestic position.

1. 1

   Decide what you are implementing and why

   Settle the question of whether you are implementing for a legal obligation, for data quality, or to serve EU visitors. The answer determines whether you run basic or advanced consent mode, and whether tags should be blocked entirely before consent or allowed to send cookieless signals. Implementing without settling this produces a configuration nobody can explain later.

2. 2

   Choose basic or advanced consent mode

   In basic consent mode, Google tags do not fire at all until consent is granted. In advanced, tags load and send cookieless pings that Google uses for modelling. Advanced preserves more measurement; basic sends nothing until permission exists. This is a genuine trade-off and it should be a documented decision, not a default.

3. 3

   Set the default consent state before anything else loads

   Your default consent command must run before any Google tag. In GTM this means a consent initialisation trigger, which fires ahead of all other triggers. If the default state loads after your tags, you have implemented nothing — the tags have already fired under whatever they assumed.

4. 4

   Map your banner to the four consent parameters

   Consent Mode v2 uses ad_storage, analytics_storage, ad_user_data and ad_personalization. Confirm your consent platform updates all four, not just the first two. The two ad parameters introduced in v2 are the ones most commonly left unset by older implementations carried forward from v1.

5. 5

   Set consent checks on every relevant tag

   In each tag configuration, set the additional consent checks so the tag requires the consent types it actually depends on. A tag with no consent requirement will fire regardless of what the visitor chose, which is the single most common implementation fault.

6. 6

   Verify with GTM preview and the browser console

   Use preview mode and step through both paths: accept, and decline. Watch the consent state update in the data layer and confirm which tags fired in each case. Then repeat in a normal browser window with developer tools open, because preview mode behaves differently from production in ways that matter.

7. 7

   Confirm the state persists across pages

   Navigate to a second and third page after making a choice and check the consent state is retained rather than reset to default. A banner that reappears on every page, or a consent state that resets, means storage is not working and nothing downstream can be trusted.

8. 8

   Propagate consent to your server container if you run one

   If you use server-side tagging, confirm the consent state reaches the server container and is respected there. A client-side refusal that never reaches the server means your server continues sending data the visitor declined.

9. 9

   Record the configuration somewhere outside the tool

   Write down which mode you chose, which tags require which consent types, and the date. Tag manager configurations get edited by people who were not there for the original decision, and the reasoning is never in the interface.