Advanced consent mode is a way of implementing Google’s consent mode in which Google’s tags load as soon as a page opens, before the visitor has made a cookie choice, and change what they send depending on that choice. If the visitor refuses, the tags send cookieless pings to Google instead of full tracking data.
How advanced consent mode works
Consent mode is the system Google tags use to read the choice a visitor makes on your cookie banner. It uses four main signals. analytics_storage and ad_storage control whether cookies may be used for analytics and advertising. ad_user_data and ad_personalization, added in version 2, control whether user data may be sent to Google for advertising and whether it may be used for personalised ads.
In advanced mode, each page follows this sequence:
- The page sets a default consent state, which for UK visitors should be denied for everything that is not strictly necessary.
- Google’s tags load straight away. While consent is denied, they send pings that neither read nor write Google cookies. The pings carry details such as the time, the browser’s user agent, the referring page, the consent state and whether the visit came from an ad click, and like any request from a browser they reach Google with the visitor’s IP address.
- If the visitor accepts, the tags switch to full measurement with cookies. If they refuse, the pings continue for the rest of the visit.
Google uses those pings to model the conversions and behaviour it could not observe. In basic consent mode, by contrast, Google’s tags do not load at all until the visitor accepts, so nothing is sent for people who refuse, and Google relies on a general model with less detail.
Why it matters
Google requires consent signals for visitors from the UK and the European Economic Area. Since 2024, Google Ads accounts that do not send them lose features such as remarketing audiences and some conversion measurement for those visitors. A UK business advertising on Google therefore needs consent mode in some form, and the real decision is between basic and advanced.
Advanced mode gives Google more to work with, which usually means more modelled conversions in Google Ads and, where the property meets Google’s thresholds, modelled behaviour in GA4. The trade-off is legal rather than technical. PECR requires consent before information is stored on, or read from, a visitor’s device unless that is strictly necessary for a service they asked for. The ICO has long made clear that the rule covers scripts, pixels and similar techniques as well as cookies. A cookieless ping still runs Google’s code in the visitor’s browser and sends information from it to Google for advertising measurement before the visitor has agreed. Calling it cookieless does not, on its own, take it outside PECR.
At the time of writing (October 2026), the Data (Use and Access) Act 2025 brings some limited exemptions into PECR’s consent rule, but they cover purposes such as measuring and improving your own service, not sending data to an advertising platform for its own modelling. Check the ICO’s current guidance before relying on any exemption. My view is that this is a decision each business should make with its data protection adviser and record in writing. Basic mode carries the lower risk. If you choose advanced mode, your banner and privacy notice should explain, in plain words, what is sent before consent.
Common mistakes
- Defaulting consent to granted, or setting the default after Google’s tags have already fired, so data leaves the page before the visitor chooses.
- Updating only ad_storage and analytics_storage and leaving the two version 2 signals unset, which limits Google Ads features even for people who accept.
- Assuming a consent platform’s Google integration works without checking it in Tag Assistant.
- Reading modelled conversions as observed ones, or expecting modelling in an account with too little data for Google to model from.
- Describing the site as cookieless in its privacy notice while Google’s tags send data before consent.
How to act on it
Begin with an inventory. Open your site in a private window, watch in Tag Assistant what fires before you touch the banner, and note the default consent state. Then accept, reload, refuse and reload again, checking that all four signals change as they should.
Decide between basic and advanced mode deliberately, with your data protection lead if you have one, and write down why. If you run Google Ads, the consent set-up is one of the first things I check in PPC management, because bidding and audiences can only be as good as the conversion data it lets through.