Google Consent Mode passes a visitor’s cookie choices to Google tags, which then change how they store cookies and what they send. It uses four signals: analytics storage, advertising storage, advertising user data, and ad personalization. Basic mode keeps Google tags blocked until the visitor consents. Advanced mode loads them and sends cookieless signals while consent is denied.
What is Google Consent Mode?
Consent Mode is the interface between your consent banner and Google’s tags. Your CMP or site code sends the visitor’s choices through the gtag consent commands, and Google Analytics and Google Ads tags adjust their behavior to match. When a visitor denies a category, the tags do not store the cookies that category would allow.
The consent decision is still yours to make. Consent Mode does not provide a banner or decide what needs consent. It only carries the decision to Google’s products, so the banner and its wording have to be right before the signals mean anything.
What are the four consent parameters?
Google’s consent guide defines four parameters. Each one covers a different use of data, so a single “accept all” flag hides choices that matter for reporting and for advertising.
| Parameter | What it controls |
|---|---|
| analytics_storage | Whether analytics cookies may be stored. Denied means Google Analytics does not set analytics cookies for that visitor. |
| ad_storage | Whether advertising cookies may be stored. Google’s guide says that when it is denied, new cookies won’t be set for advertising purposes. |
| ad_user_data | Whether user data may be sent to Google for advertising. The guide describes it as consent for sending user data related to advertising to Google. |
| ad_personalization | Whether data may be used for personalized advertising, such as remarketing audiences. |
What changed in Consent Mode v2?
Version 2 added two parameters to the original pair. Google’s note on consent mode updates for EEA traffic says the consent mode API now includes ad_user_data and ad_personalization, and that advertisers must share consent signals with Google for personalization, remarketing, and measurement.
If you use a Google-certified CMP, Google says the provider updates to the newest version of consent mode, but confirm that your banner maps each category to all four parameters. If you built your own banner, you have to add the two new parameters yourself.
How do basic and advanced consent mode differ?
The choice between basic and advanced is about timing. Basic mode waits for the visitor. Advanced mode starts measurement immediately and changes what it sends based on the answer.
| Basic consent mode | Advanced consent mode | |
|---|---|---|
| Before the visitor chooses | Google tags stay blocked until the visitor interacts with the banner. | Google tags load when the page opens, with denied defaults applied. |
| If the visitor denies consent | Nothing is sent to Google for that visitor. | Tags send cookieless pings with no cookies. |
| If the visitor grants consent | Tags load and send full measurement data after the choice. | Tags send full measurement data after the choice. |
| Effect on modeling | Google’s documentation says Ads conversion modeling falls back to a general model. | Cookieless pings feed advertiser-specific conversion modeling. |
Google’s help pages say the cookieless pings are used to model metrics, so advanced mode can recover some conversions and behavior that basic mode would leave unmeasured. It also means tags run before a decision, so the defaults and the banner must be set up correctly from the first page load. Google’s consent guide stresses that defaults must be set on every page before any measurement command runs.
How does consent mode change GA4 and Google Ads reports?
Google’s consent pages say cookieless pings are used for modeling to fill gaps in the data for visitors who decline. The modeled figures are estimates built from the behavior of consenting visitors.
In Google Analytics, the modeling covers behavior and conversions, and Google notes that your tags need to meet a data collection threshold before modeling applies. In Google Ads, basic mode uses a general conversion model, while advanced mode uses an advertiser-specific one. Reconcile platform totals with your own consented records, and read a gap as a consent-rate question before treating it as a tracking bug. For a broader view of why platform numbers differ, see why Google Ads and GA4 conversions don’t match.
The practical difference shows up in the report, not only in the code. A basic setup can show fewer conversions from users who decline, because nothing reaches Google from them. An advanced setup sends cookieless signals from them, so the gap is filled by modeling rather than left empty. Neither setup recovers the data a visitor withheld; both change how the missing part is estimated.
When is Consent Mode required in the EEA, UK and Switzerland?
Google’s Google Ads help pages say consent is required in the European Economic Area, the United Kingdom, and Switzerland. The Verify your consent signals page states that the ad_user_data parameter is required for regions that require end-user consent, and it names those three areas. Its help pages also link to Google’s EU user consent policy.
Those pages do not decide your legal position. Whether you need a consent banner, what it must say, and which vendors need permission are questions for your privacy counsel. Treat the Google requirements as the platform’s minimum for signal handling, and confirm the rest with your advisers before you launch.
Which mode to use is a decision for the team that owns the consent banner and the legal review, with the marketing team in the room. Google’s pages describe both modes without ranking them. Basic mode keeps Google tags out of the page until a choice is made. Advanced mode lets the tags run and depends on the defaults and updates being right. Either way, write the choice down, because it determines what a future analyst should expect in the GA4 and Google Ads numbers.
How do you check that consent mode works?
Google’s debugging guide uses Tag Assistant as the main check. Confirm each point below on your own site, in a fresh browser session, before and after you accept and reject the banner.
- Open Tag Assistant and find the earliest Consent event. The default values should appear in the API call section and in the on-page default column before any tag fires.
- Open the most recent Consent event and confirm the updated values match the visitor’s choice.
- Click a Google tag in Tag Assistant and check that its behavior follows the consent state.
- Repeat the test from a location in each region you serve, using the Chrome location setting Google’s guide describes.
- If Tag Assistant shows an empty Consent tab, consent mode is not running on the page.
Google’s consent guide recommends an update mechanism for every parameter you set a default for, so a choice made later on the page is reflected in the tags. For the full testing sequence, use the tracking QA checklist before launch.
Testing once at launch is not enough. Banner changes, new tags, a CMP upgrade, or a tag manager publish can each break the order of defaults and updates. Repeat the Tag Assistant checks after each release that touches tags or the banner, and keep a dated record of the results alongside your tracking documentation.
What mistakes break Consent Mode?
| Mistake | What to check |
|---|---|
| Defaults set after tags fire | Google’s guide says the order of the code is vital, and that defaults set out of order will not work. A tag that reads or writes a cookie before the default is set is flagged in Tag Assistant. |
| Defaults set asynchronously | Google warns against setting default consent states asynchronously. Put the default in the page code ahead of the Google tag. |
| Missing parameters or updates | Set a default for each of the four parameters, and make sure there is an update path for every one you default. |
| Region settings that do not match | A regional default that covers some parameters but not others leaves the rest on the global default. Map each parameter for each region. |
| Blocking the Google tag | Google’s debugging guide says blocking the Google tag makes modeled conversions less accurate, even when consent mode is set. |
| Consent calls in custom HTML | Google discourages calling the consent command from a custom HTML tag in Tag Manager and recommends a template tag. |
One mistake sits outside the tags entirely: a banner that does not record choices correctly. Consent Mode passes along what the CMP reports, so a CMP that misreads a choice sends the wrong signal to every tag. Confirm with your CMP vendor how it integrates with Consent Mode in each region you serve.
Does consent apply to server-side tagging?
Yes. Moving tags to a server does not remove the consent requirement. The server still has to receive and honor the visitor’s choice before it forwards data to Google or another vendor. Review the configuration and destinations as you would for client-side tags. For the setup, read the server-side tagging guide. For a broader check of how consent, tags, and conversion data fit together, see the marketing tracking audit checklist, and if you need a second pair of eyes on your setup, contact us.
Frequently asked questions
What is Google Consent Mode?
Google Consent Mode is a way to pass a visitor’s cookie consent choices to Google tags, such as Google Analytics and Google Ads tags. The tags read the choices and change what they do: when storage is denied they do not set advertising cookies, and depending on the setup they may send cookieless signals instead. It is configured through your consent banner or consent management platform (CMP); it does not display a banner by itself.
What is the difference between basic and advanced consent mode?
In basic consent mode, Google tags stay blocked until the visitor interacts with the consent banner, so nothing is sent to Google before a choice is made. In advanced consent mode, Google tags load when the page opens, and while consent is denied they send cookieless pings. Google uses those pings for modeling, which fills some of the gaps left by users who decline.
When is Google Consent Mode required?
Google Ads help says consent is required in the European Economic Area (EEA), the United Kingdom, and Switzerland, and that the ad_user_data parameter is required for regions that require end-user consent. Google also says advertisers must share consent signals with it for personalization, remarketing, and measurement. Confirm your wider legal obligations with your privacy advisers.
How do you check that consent mode is working?
Open Google Tag Assistant on your site and check the Consent events. The earliest event should show the default states set before any tag ran, and later events should show the updates made when a visitor chose. Click individual tags to see whether they respected the consent settings. Then repeat the test from a browser or location in each region you target.
Sources and references
- Google for Developers: Consent mode (tag platform security guide)
- Google for Developers: Debug consent mode
- Google Analytics Help: About consent mode
- Google Ads Help: About consent mode
- Google Ads Help: Updates to consent mode for traffic in the EEA
- Google Ads Help: Verify your consent signals for EEA users
- Google Ads Help: Verify your consent signals