Google\u2019s Consent Mode<\/a> is a way to control how tags react to the user\u2019s consent for different tracking purposes. It is specifically designed to work with Google\u2019s tags<\/strong>, but especially through Google Tag Manager, you can use Consent Mode\u2019s features and APIs to control other tags, too.<\/p>\n Consent Mode comes in two \u201cflavors\u201d:<\/p>\n Advanced Consent Mode<\/strong> is specifically designed for Google\u2019s products. Tags for GA4, Ads, and Floodlight are sensitive<\/em> to the user\u2019s consent choices and change their behavior accordingly. Advanced Consent Mode is very easy to implement<\/strong> because it basically requires no changes to tags\u2019 existing triggering mechanisms.<\/p>\n<\/li>\n Basic Consent Mode<\/strong> means that tags wait<\/em> until appropriate consent has been granted. This means that they need to be manually blocked from firing until the user signals that they consent to tracking for whatever purpose each tag has. Basic Consent Mode is very difficult to implement<\/strong> because the triggering mechanisms are very awkward to implement.<\/p>\n<\/li>\n<\/ul>\n <\/p>\n <\/a><\/p>\n<\/div>\n In this guide, I will walk you through the latter. Basic Consent Mode is a total headache, because unlike Advanced Consent Mode, there\u2019s nothing automated about it at all. Basic Consent Mode basically means that tags should only ever fire when relevant consent has been granted. If consent has not been granted or if it\u2019s unclear if there is consent, the tags should not fire<\/em>.<\/p>\n The first part of the guide<\/a> will discuss how to implement Consent Mode itself, either through a Consent Management Platform (CMP)<\/a>, manually with a custom template<\/a>, or with a hybrid of the two. The second part of the guide<\/a> covers how to adjust your tags to fire only when appropriate consent is granted.<\/p>\n This article will focus on a Google Tag Manager<\/strong> implementation first and foremost. If you\u2019re using just Google Tag, go ahead and read this guide as much of it is still very relevant. However, you should also consult the official guide<\/a>.<\/p>\n \n \n Subscribe to the Simmer newsletter<\/a> to get the latest news and content from Simo Ahava into your email inbox!\n <\/p>\n <\/span><\/p>\n Basic Consent Mode (BCM) isn\u2019t really a feature<\/em>. It\u2019s an implementation approach<\/em> that specifies that tags which require consent should never fire until the consent that they require has been granted<\/strong>.<\/p>\n It\u2019s basically business as usual. This is how you probably orchestrated your tags anyway due to legislation like GDPR and ePrivacy dictating legal bases for processing user data.<\/p>\n However, with BCM, you need to link your tags to how Consent Mode itself has been activated on the page. This means that your Consent Management Platform (CMP) needs to be integrated<\/strong> with Consent Mode. If it isn\u2019t, you need to engineer the cooperation between your CMP and Consent Mode yourself.<\/p>\n <\/p>\n <\/a><\/p>\n<\/div>\n Consent Mode has two different types of calls.<\/p>\n Both calls take an object as one of the arguments. This object includes the different consent signals and their states. If consent for a specific signal is denied, the value should be We will be ignoring all the custom consent signals ( When consent is then granted for analytics, for example, the Update call would be sent with this object:<\/p>\n Here is what I consider the ideal approach. We will be covering this in more detail in subsequent steps of the guide. It\u2019s important to understand that this approach requires a cooperative CMP. If the Consent Management Platform has a quirky integration with Consent Mode, it\u2019s possible you\u2019ll need to pick up the slack and control Consent Mode calls yourself using the appropriate template.<\/p>\n The Default<\/strong> call should always happen on the Consent Initialization – All Pages<\/strong> trigger, and it should set all consent signals to <\/p>\n <\/a><\/p>\n<\/div>\n You might ask why not set the consent signals to If consent is known already when the GTM container loads<\/strong>, the Update<\/strong> call should happen immediately after the Default<\/strong> call, also on the Consent Initialization<\/strong> trigger. The Update<\/strong> call should be immediately followed by a <\/p>\n <\/a><\/p>\n<\/div>\n By running the Default and Update calls with the latter coming immediate after the former, you ensure that all GTM tags can make use of the most current consent states as soon as they are set to fire.<\/p>\n If consent is set<\/strong> or changed<\/strong> by the user later, or if the consent state is only known once the CMP has loaded, for example, the Update<\/strong> call should happen immediately when the state of these consent signals is known. Again, this Update<\/strong> call should be immediately followed by a <\/p>\n <\/a><\/p>\n<\/div>\n In the screenshot above, the Consent Update call is done by a GTM custom template (see below<\/a>) that fires on the As you can see, the consent update happens already on the The ideal approach thus makes use of GTM\u2019s templates to engineer consent. Relying on In the rest of the guide, we\u2019ll deconstruct this ideal approach and look at it from the viewpoint of how most CMPs work.<\/p>\n I cannot recommend any CMPs over others. I\u2019ve always preferred to orchestrate interactions with Consent Mode manually, using a custom template (see below<\/a>), but there are many CMPs that have their own custom templates that do the job, more or less.<\/p>\n Generally, I\u2019d recommend loading the CMP outside GTM<\/strong>, before Google Tag Manager loads. This is because in some cases GTM is blocked by ad and content blockers, which means your CMP is never loaded at all. This poses a risk in case you have data collection subject to user consent happening outside GTM.<\/p>\n<\/blockquote>\n In any case, when working with a CMP, you need to be careful how much of Consent Mode logic you delegate to the CMP library itself, as it\u2019s often loaded asynchronously<\/strong>. Asynchronous loading means that the browser initiates the load but then proceeds to execute other tasks in the queue. In other words, there\u2019s no guarantee when<\/em> the CMP has actually loaded and is ready to implement Consent Mode.<\/p>\n Regardless of how the CMP works, here is how I recommend engineering Consent Mode:<\/p>\n Use a GTM custom template to set the Default<\/strong> to Use a GTM custom template to fire an Update<\/strong> call on Consent Initialization – All Pages<\/strong> trigger if<\/em> the user has already established consent previously and this is available in browser cookies or Use a GTM custom template to fire an Update<\/strong> call whenever the user adjusts their consent choices.<\/p>\n<\/li>\n<\/ol>\n Now, ideally, it would be the CMP\u2019s own<\/strong> custom template that handles all of the above. However, CMPs often lack a proper GTM template, or they opt to use As a positive example, the Cookiebanners.nl<\/a> template handles this nicely. You need to set a tag created with this template to fire on the Consent Initialization – All pages<\/strong> trigger. The tag will then automatically run the Default call when it first fires, followed by an Update call if the Cookiebanners.nl consent states are available in a browser cookie<\/strong>. Later, if the user adjusts their consent choices, the Cookiebanners.nl JavaScript library runs a <\/p>\n <\/a><\/p>\n<\/div>\n If you are working for a CMP or shopping around for a CMP that works ideally with Consent Mode, here are the features it should have:<\/p>\n It needs a dedicated GTM Custom Template<\/strong> that utilizes the custom template consent APIs: The custom template needs to push a Data Layer event<\/strong> as soon as any Update<\/strong> call is made. This is because the Consent Update call itself cannot be used as a GTM trigger!<\/strong>. If you want to trigger tags when the user\u2019s consent choices are known or when they change, the CMP must<\/strong> push an event to For inspiration, see how the Cookiebanners.nl template has been created<\/a>. Full disclosure, I helped build it.<\/p>\n If you want to take control over at least the crucial initialization flow, you can use my Consent Mode (Google + Microsoft Tags)<\/a> template available in the Community Template Gallery<\/a>.<\/p>\n If you do this, it\u2019s important that the CMP doesn\u2019t interact with Consent Mode itself<\/strong>, otherwise you might have a situation where multiple, often conflicting Update or Default calls happen. The CMP\u2019s job is to write the user\u2019s consent choices into browser storage (cookies or Here\u2019s an example of an ideal setup:<\/p>\n\n
![\"Tag](\"https:\/\/www.simoahava.com\/images\/2025\/05\/tags-blocked.jpg#ZgotmplZ\")
<\/p>\n
\n X<\/span><\/p>\n
\n The Simmer Newsletter<\/strong>\n <\/p>\nBasic Consent Mode: the basics<\/h2>\n
![\"Consent](\"https:\/\/www.simoahava.com\/images\/2025\/05\/consent-default-update.jpg#ZgotmplZ\")
<\/p>\nThe Consent Mode calls<\/h3>\n
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denied<\/code> by default<\/strong>, even<\/em> if you already know the user\u2019s consent choices by the time the default call is made (more on this below<\/a>).<\/li>\n\"denied\"<\/code>. If consent has been granted, the value should be \"granted\"<\/code>. Here\u2019s an example where consent is denied by default:<\/p>\n{\n ad_storage: \"denied\"<\/span>,\n analytics_storage: \"denied\"<\/span>,\n ad_user_data: \"denied\"<\/span>,\n ad_personalization: \"denied\"<\/span>\n}\n<\/code><\/pre>\n<\/div>\n\n
funcionality_storage<\/code>, security_storage<\/code> etc.) as they are not officially part of Consent Mode.<\/p>\n<\/blockquote>\n{\n ad_storage: \"denied\"<\/span>,\n analytics_storage: \"granted\"<\/span>, \/\/ Consent granted for analytics\n<\/span> ad_user_data: \"denied\"<\/span>,\n ad_personalization: \"denied\"<\/span>\n}\n<\/code><\/pre>\n<\/div>\nThe ideal approach<\/h3>\n
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\"denied\"<\/code>.<\/p>\n<\/blockquote>\n![\"Consent](\"https:\/\/www.simoahava.com\/images\/2025\/05\/consent-default.jpg#ZgotmplZ\")
<\/p>\n\"granted\"<\/code> already in the Default call, in case that information is available in the cookies (or other browser storage) the CMP sets. Setting defaults to \"denied\"<\/code>, in my opinion, is the most elegant and most consistent approach. By relying solely<\/em> on Update calls, you eliminate possible race conditions that emerge from the consent information not being available at Default time.<\/p>\n\n
dataLayer.push<\/code> call with a custom event (e.g. gtm_consent_update<\/code>) and details about the consent states. This event is used for triggering tags that need consent.<\/p>\n<\/blockquote>\n![\"Consent](\"https:\/\/www.simoahava.com\/images\/2025\/05\/consent-update.jpg#ZgotmplZ\")
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dataLayer.push<\/code> as explained above.<\/p>\n<\/blockquote>\n![\"Consnet](\"https:\/\/www.simoahava.com\/images\/2025\/05\/consent-update-click.jpg#ZgotmplZ\")
<\/p>\nconsent_banner_click<\/code> event.<\/p>\n\n
consent_banner_click<\/code> event. This is because GTM is specially engineered to immediately apply changes to consent states if the custom template uses the dedicated template APIs (setDefaultConsentState<\/code><\/a> and updateConsentState<\/code><\/a>).<\/p>\n<\/blockquote>\ngtag<\/code> alone does work, but it introduces potential race conditions<\/em> where the consent state takes longer than anticipated to be set.<\/p>\nThe Consent Management Platform<\/h2>\n
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\"denied\"<\/code> across the board, and have it fire on the Consent Initialization – All Pages<\/strong> trigger. Set the Tag Priority<\/strong> of this tag to 10<\/code>, for example.<\/p>\n<\/li>\nlocalStorage<\/code>. Adjust the states from \"denied\"<\/code> to \"granted\"<\/code> for all signals whose consent has been granted (you might need to use variables to pull in the consent state from cookies or localStorage<\/code> or the global window<\/code> object).<\/p>\n<\/li>\ngtag<\/code> instead of using the dedicated template APIs. In this case, it might be best to orchestrate Consent Mode manually<\/a>.<\/p>\ngtag('consent', 'update', ...)<\/code> call to update consent states, followed by a dataLayer.push()<\/code> with an event that can be used to trigger tags with.<\/p>\n![\"Cookiebanners.nl\"\/](\"https:\/\/www.simoahava.com\/images\/2025\/05\/cookiebanners.jpg#ZgotmplZ\")
<\/p>\nInstructions for CMP designers on how to implement Consent Mode<\/h3>\n
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setDefaultConsentState<\/code><\/a> and updateConsentState<\/code><\/a>. The first should be called immediately when a tag built with the template fires (call it just once per page load, though!), and the second should be called immediately after this, if consent is already known<\/em>. If the user changes their consent settings, updateConsentState<\/code> should be called again. These APIs are special<\/strong> in that they immediately toggle the consent states in Google Tag Manager instead of having to wait for the container to process a gtag()<\/code> call.<\/p>\n<\/li>\ndataLayer<\/code> that can then be used as the trigger event. The dataLayer.push()<\/code> call could look like this, for example:<\/p>\n<\/li>\n<\/ol>\nwindow<\/span>.dataLayer.push({\n event: 'gtm_consent_update'<\/span>,\n analytics_storage: 'granted'<\/span>,\n ad_storage: 'denied'<\/span>,\n ad_user_data: 'denied'<\/span>,\n ad_personalization: 'denied'<\/span>\n});\n<\/code><\/pre>\n<\/div>\n\n
Patching the CMP manually with a custom template<\/h3>\n
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localStorage<\/code> for example), and then push an event to dataLayer<\/code> that can be used to trigger the custom template tag with.<\/p>\n<\/blockquote>\n\n
\"denied\"<\/code>.<\/li>\n10<\/code>.<\/li>\n<\/ol>\n
![\"Custom](\"https:\/\/www.simoahava.com\/images\/2025\/05\/custom-template-default.jpg#ZgotmplZ\")
<\/p>\n![\"Example](\"https:\/\/www.simoahava.com\/images\/2025\/05\/example-custom-template-approach.jpg#ZgotmplZ\")
<\/p>\n![\"push-datalayer-event-option.jpg\"\/](\"https:\/\/www.simoahava.com\/images\/2025\/05\/push-datalayer-event-option.jpg#ZgotmplZ\")
<\/p>\n![\"CMP](\"https:\/\/www.simoahava.com\/images\/2025\/05\/cmp-datalayer-event.jpg#ZgotmplZ\")
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