A plain English guide to Consent Mode v2

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Consent Mode v2 gets described as a checkbox: you have it or you do not. In practice it is a small protocol with four signals and two very different implementations, and the difference decides how much of your data survives a rejected banner.

What are the four Consent Mode v2 signals?

Consent Mode is how your banner tells Google's tags what the visitor allowed, and passing these signals is one half of what a consent management platform does; capturing and proving the choice is the other. It speaks through four switches. analytics_storage covers measurement cookies, the ones GA4 uses to recognise a returning session. ad_storage covers advertising cookies, used for attribution. Version 2 added two more: ad_user_data, which says whether data about the user may be sent to Google for advertising, and ad_personalization, which says whether that data may power personalised ads and remarketing.

Since March 2024, Google requires the v2 signals for audiences in the European Economic Area and the UK if you want ad personalisation and measurement features to keep working. Without them, features degrade regardless of what your banner looks like.

What is the difference between basic and advanced?

The same four signals can be implemented two ways, and the names undersell the difference.

Basic means Google tags do not load at all until the visitor consents. Clean and simple, but when someone rejects, Google receives nothing, not even the anonymous signal that a visit occurred. There is nothing to model from, so rejected traffic is simply gone.

Advanced means tags load before the choice, respect it completely once made, and send cookieless pings when consent is denied. No cookies are set and no identifiers are stored, but Google learns that an anonymous conversion happened. Those pings are the raw material for conversion modelling. Google can use them to estimate some denied conversions, but only when your account meets its eligibility thresholds.

How to tell which one you are running

1. Open your site in a private window

   Open the browser network tab before touching the banner, and filter for requests to Google domains. What fires before you make a choice is the whole diagnostic.

2. Read what happens before you consent

   If no Google requests appear at all until you accept, you are on basic. If requests fire with gcs or gcd parameters showing a denied state, you are on advanced.

3. Confirm the defaults in Tag Assistant

   The consent tab shows the four signals and their state on page load. The defaults should be set before any tag fires, then update when the visitor chooses.

For the full walkthrough, including how to decode the gcs code and rule out a broken tag that only looks like basic mode, see basic vs advanced Consent Mode, which one you are running.

Velo ships the advanced implementation by default, sets the default state before your tags fire, and keeps a consent log so you can prove what was set and when.

Your next step in website privacy.

Velo sets your consent defaults, passes the four signals to Google’s tags and keeps a record of every choice your visitors make.