Basic consent mode is a way of implementing Google’s consent mode in which Google tags, such as GA4 and Google Ads, are blocked completely until the visitor agrees on your cookie banner. If the visitor declines or ignores the banner, Google receives nothing from that visit.
How basic consent mode works
Consent mode is Google’s system for telling its tags what a visitor has agreed to. It uses four signals: analytics_storage and ad_storage, which cover cookies for measurement and advertising, and ad_user_data and ad_personalization, which cover sending user data to Google for advertising and using it to personalise ads. Your consent management platform, the tool that runs your banner, sets each signal to granted or denied.
In basic mode the tags themselves wait. Nothing from Google loads while the banner is showing. When the visitor accepts, the tags load with the consent state and behave normally for that visitor from then on. When the visitor declines, the tags never load, so there are no cookies, no pings and no record of the visit.
The alternative is advanced consent mode. There, Google tags load straight away with consent denied by default, and send cookieless pings for visitors who decline, which Google uses to estimate the conversions and behaviour it cannot observe.
Why it matters
For a UK website, choosing between basic and advanced is mainly a question of how you read PECR, the regulations covering cookies and similar technologies. PECR requires consent before storing or accessing information on a visitor’s device unless it is strictly necessary for the service they asked for. Basic mode is the conservative reading: no Google measurement code runs, and nothing is read from or sent about the device, until the visitor has said yes. Advanced mode depends on the cookieless pings falling outside that requirement, which is a less certain position, and the ICO has been actively reviewing how UK websites handle cookie consent.
The Data (Use and Access) Act 2025 added a limited exemption for some analytics used only to improve your own service. At the time of writing (October 2026) I would not rely on it for Google tags that also feed advertising, and the ICO’s current guidance is the place to check whether a particular setup qualifies.
The cost is data. In basic mode, everyone who declines is invisible: they do not appear in GA4, their conversions are not reported to Google Ads, and Smart Bidding learns only from those who accepted. Google still provides some modelled conversions in basic mode, but from a general model rather than one built from your own site’s unconsented traffic, so expect less of the gap to be filled than advanced mode would manage.
Common mistakes
- Assuming a banner on its own is basic consent mode. If tags load before consent and the banner simply records a choice afterwards, the site is neither compliant nor in basic mode.
- Sending only two of the four signals. Without ad_user_data and ad_personalization, Google Ads audience and remarketing features stop working for UK visitors under Google’s EU user consent policy.
- Blocking GA4 but leaving a Google Ads tag, a Meta pixel or a chat widget firing before consent.
- Reading the drop in GA4 sessions after switching to basic mode as lost traffic. It is lost measurement.
- Making “Reject” harder to find than “Accept”. The ICO expects refusing to be as easy as agreeing, and a lopsided banner undermines the consent you collect.
How to act on it
Start with a cookie audit. Load your site in a fresh private window, leave the banner alone, and check in the browser’s developer tools which requests go out and which cookies are set. In basic mode there should be no requests to Google Analytics or Google Ads until you click accept. Then accept, and confirm in Google’s Tag Assistant that all four consent signals arrive as granted.
Choose between basic and advanced deliberately, write down why, and describe the result accurately in your cookie policy. If basic mode leaves too few conversions for Smart Bidding, improve what you can collect lawfully: enhanced conversions for visitors who consent, offline conversion imports from your CRM, and a banner that explains plainly what measurement is for. Keeping paid campaigns supplied with lawful conversion data is a core part of performance marketing for UK sites.