Google Consent Mode v2 is a framework that sits between your cookie consent banner and Google's tracking tags. It translates your visitors' consent choices into signals that Google Analytics 4, Google Ads, and other Google services understand, adjusting their data collection behaviour accordingly. Since March 2024, implementing it has been mandatory for any website using Google's advertising or measurement products with visitors in the European Economic Area (EEA).
The update was driven by the EU's Digital Markets Act (DMA), which designated Google as a gatekeeper and imposed strict rules on how it handles user consent. Google responded by tightening its EU User Consent Policy and requiring advertisers to pass granular consent signals for every EEA user interaction.
What Changed from Consent Mode v1 to v2
The original Consent Mode offered two parameters: ad_storage (controlling whether advertising cookies could be written) and analytics_storage (controlling analytics cookies). These were useful but blunt instruments - they only governed whether cookies were placed, not what happened with the data afterwards.
Consent Mode v2 introduced two additional parameters that separate data collection from data activation:
| Parameter | Controls | Version |
|---|---|---|
ad_storage | Storage of advertising cookies (e.g. _gcl_au, _gac) | v1 |
analytics_storage | Storage of analytics cookies (e.g. _ga, _ga_*) | v1 |
ad_user_data | Sending user data to Google for advertising purposes | v2 (new) |
ad_personalization | Using data for personalised ads and remarketing | v2 (new) |
These four parameters work independently. A visitor might grant ad_user_data (allowing conversion measurement) while denying ad_personalization (declining remarketing). This granular separation is what the GDPR and DMA demand - specific, informed consent for each distinct purpose.
Basic Mode vs Advanced Mode
Consent Mode v2 can be deployed in two ways, and the choice has significant consequences for your data.
Basic Consent Mode blocks all Google tags from firing until a visitor grants consent. If someone clicks "Reject All" on your cookie banner, nothing is sent to Google - no cookies, no pings, no signals. Google Ads then relies on a general, less precise model to estimate conversions. For websites with low consent rates, this can mean substantial blind spots in your reporting.
Advanced Consent Mode loads Google tags immediately, but in a restricted state. Before consent is granted (and if consent is denied), the tags send cookieless pings to Google's servers. These pings contain no personal identifiers and no cookies are stored, but they do transmit contextual signals such as the timestamp, user agent, and whether a conversion occurred. Google uses these anonymised signals to build an advertiser-specific model of non-consented user behaviour.
The practical difference is stark. Advanced Mode typically recovers around 65-70% of conversion attribution data that would otherwise be lost when visitors decline cookies. Basic Mode relies on broader statistical modelling that is inherently less accurate because Google has no site-specific signals to work with.
A Legal Caveat on Advanced Mode
Advanced Mode sends cookieless pings before consent is granted. Whether those pings constitute personal data processing under Article 5(3) of the ePrivacy Directive is still debated among data protection professionals. Some stricter interpretations - particularly in Germany - treat any data transmission from a user's device as requiring prior consent. Consult your legal team before choosing Advanced Mode, especially if you serve visitors in jurisdictions with aggressive enforcement.
How Conversion Modelling Works
When a visitor rejects cookies but Advanced Consent Mode is active, Google collects anonymised signals - device type, browser, country, time of day, and whether a conversion event was triggered. No identifying cookies are set and no personal data is stored.
Google's machine learning then compares this anonymous cohort against the behaviour of consented users on the same website. If 4.5% of consented visitors convert after clicking an ad, and 100 cookieless pings were received from non-consented visitors, the model estimates roughly 4.5 conversions for that group. The algorithm also corrects for behavioural differences between consenting and non-consenting populations, since these groups often convert at different rates.
Modelling does not activate automatically. Google Analytics 4 requires at least 1,000 daily users with analytics_storage='granted' for seven of the last 28 days, plus at least 1,000 daily events with analytics_storage='denied' for seven days. Google Ads needs a minimum of 700 ad clicks per day over seven consecutive days per country and domain. Smaller sites and lower-budget advertisers may never reach these thresholds.
What Happens If You Do Not Implement Consent Mode v2
Google began enforcing its EU User Consent Policy in March 2024 and has progressively tightened enforcement since. Websites that fail to pass consent signals for EEA visitors lose access to several features:
- Remarketing audiences - Google will not populate remarketing lists without a valid
ad_personalizationsignal - Conversion tracking - without
ad_user_data, Enhanced Conversions and GA4 conversion exports to Google Ads stop functioning - Ad personalisation - campaigns fall back to broad, contextual targeting only
- Audience building - customer match and similar audience segments are unavailable
In September 2025, the French CNIL fined Google 325 million euros for showing promotional ads in Gmail without prior consent and for using consent designs that steered users towards personalised advertising. The decision reinforced that consent flows must be neutral, freely given, and genuinely informed - principles that apply just as much to your own website's banner as to Google's products.
How to Implement Consent Mode v2
There are three main implementation paths. The right one depends on your technical setup.
Option 1: Use a Google-Certified CMP
The simplest route is a consent management platform that is a certified Google CMP Partner. A certified CMP handles all four consent parameters automatically, maps your banner choices to the correct granted or denied states, and transmits them to Google tags in real time. Kukie.io supports Google Consent Mode v2 natively - the integration can be enabled in the banner settings without touching your site's code.
Option 2: Google Tag Manager
If you manage tags through Google Tag Manager, you can configure consent settings within GTM's built-in consent framework. Set default consent states (typically all denied for EEA visitors) using the Consent Initialisation trigger, then update them via a consent mode template when your banner fires. Many CMPs provide pre-built GTM templates in the Community Template Gallery that handle this mapping.
Option 3: Manual Implementation via gtag.js
For custom setups, you add a gtag('consent', 'default', {...}) call before any Google tags load, setting all four parameters to 'denied'. When the visitor interacts with your banner, fire a gtag('consent', 'update', {...}) call with the appropriate states. The update must happen on the same page and before any page transition, or Google tags may lose critical data points such as the session_start event.
Verifying Your Implementation
After setup, verify that consent signals are reaching Google correctly. Open your site in Chrome with the Google Tag Assistant extension. Watch the consent initialisation on page load (all parameters should show denied by default for EEA visitors). Interact with your banner, then check that Tag Assistant reflects the updated consent states.
In Google Ads, check the conversion diagnostics tab - it now displays your Consent Mode status and flags missing signals. In GA4, navigate to Admin, then Property Settings, then Data Display, then Reporting Identity. Select "Blended" to include modelled data in your reports. If you leave this on "Observed", GA4 shows only directly measured data and skips modelling entirely.
Advanced Consent Mode and Enhanced Conversions
Consent Mode v2 and Enhanced Conversions solve different problems and work best together. Consent Mode handles visitors who reject cookies by modelling their likely behaviour. Enhanced Conversions handles visitors whose cookies are deleted between the ad click and the conversion - it sends hashed first-party data (email address, phone number) to Google, allowing it to match the conversion to a logged-in Google user even without cookies.
Combined, these two mechanisms can recover a significant portion of lost attribution data. Advanced Consent Mode alone recovers roughly 65-70% of conversion data from non-consenting users, while Enhanced Conversions adds another 5-25% for cookie-deleted conversions.
Does Consent Mode v2 Apply Outside the EEA?
Strictly speaking, Google's requirement targets EEA, UK, and Swiss traffic. But there are practical reasons to implement it globally. Safari's Intelligent Tracking Prevention and Firefox's Enhanced Tracking Protection restrict cookies worldwide, not just in Europe. United States state privacy laws - in California, Colorado, Virginia, Connecticut, and a growing list of others - create their own data handling requirements. Consent Mode's conversion modelling improves attribution accuracy regardless of geography. Implementing it site-wide means a consistent data pipeline and fewer edge cases to debug.
Frequently Asked Questions
Does Google Consent Mode v2 replace my cookie banner?
No. Consent Mode is a signalling layer between your banner and Google's tags. You still need a consent management platform to collect and store visitor choices. Consent Mode transmits those choices to Google so its tags adjust their behaviour.
Can I use Basic Mode and still run remarketing campaigns?
Only for visitors who consent. Basic Mode blocks all tag activity for non-consenting users, so Google receives no signals to build remarketing audiences from. If consent rates are low, your remarketing pools will shrink significantly.
Is Advanced Consent Mode fully GDPR-compliant?
It depends on your jurisdiction's interpretation. The cookieless pings sent before consent do not set cookies or use personal identifiers, but some data protection authorities consider any data transmission from a user's device to require prior consent under the ePrivacy Directive. Seek legal advice specific to the countries you serve.
How long does it take for conversion modelling to activate?
Google requires minimum traffic thresholds to be met consistently over seven days before modelling kicks in. For GA4, that means at least 1,000 consenting and 1,000 non-consenting users daily. For Google Ads, at least 700 ad clicks per day per country and domain. Smaller sites may not qualify.
What is the difference between ad_storage and ad_user_data?
ad_storage controls whether advertising cookies are placed on the visitor's device. ad_user_data controls whether any user data (including hashed first-party data from Enhanced Conversions) is sent to Google for advertising purposes. Both must be granted for full advertising functionality.
Will Consent Mode v2 affect my Google Analytics 4 reports?
Yes. If you switch from a banner that did not block tags to a compliant setup with Consent Mode, expect a drop in directly measured users and sessions. With Advanced Mode and Blended reporting identity enabled, GA4 will use modelling to partially fill those gaps - but reported numbers will likely be lower than before.
Do I need to implement Consent Mode v2 if my website has no EU visitors?
Google's requirement specifically targets EEA, UK, and Swiss traffic. If you can confirm you have zero visitors from those regions, you are not technically required to implement it. However, conversion modelling improves data accuracy globally, and privacy regulations are expanding in many other jurisdictions.
Get Your Consent Mode Implementation Right
If your Google Ads conversion tracking shows gaps or you have received a warning from Google about missing consent signals, the fix starts with a properly configured consent banner. Kukie.io supports Google Consent Mode v2 out of the box, transmitting all four consent parameters to Google tags without custom code. Run a free cookie scan to see what your site currently sets, then connect the dots.
