Consent mode
cookie consent / consent signals / why did conversions drop after the cookie banner / TCF
Consent mode is how an advertising tag is told whether a visitor agreed to be tracked. Both major platforms now require a consent signal, and the penalties differ in kind: Google's policy allows it to suspend or terminate your account, while Microsoft simply stops recording your conversions.
Google's version is a contract term, not a feature. Its EU user consent policy says that if your agreement incorporates the policy you must ensure certain disclosures are given to, and consents obtained from, end users in the European Economic Area, the UK and Switzerland. It then names the duties: obtain legally valid consent to the use of cookies or other local storage where legally required, and to the collection, sharing and use of personal data for personalization of ads. You must retain records of consent given, provide clear instructions for revoking it, and clearly identify each party that may collect, receive or use the data.
The consequence is stated in the same breath. If you fail to comply, Google may limit or suspend your use of the product and may terminate your agreement.
Microsoft arrives at the same place through the measurement door. It requires advertisers using its Universal Event Tag to provide consent signals, through either consent mode for the tag or the industry Transparency and Consent Framework. Without one of those, it says it will stop tracking your tag-based conversions and stop populating your remarketing lists. Nothing gets suspended. The numbers simply stop arriving.
Two more details save arguments later. Microsoft says either approach can be used but never both at the same time. And it warns that even with consent signals working correctly, you may see a drop in these volumes depending on what visitors actually choose. A fall after implementation is the system working, not a fault to chase.
In practice
This is why the banner is not a legal chore bolted onto the side of the site. It sits upstream of every conversion figure in the account. A site that tightens its banner will usually report fewer conversions the following month, and the honest reading is that it is now counting only the people who agreed to be counted.
Not the same as
- A cookie banner
- The banner collects the answer. Consent mode is what passes that answer to the advertising tags so they change behavior.
- Turning tracking off
- The signal tells the tag what it may do, and the platforms treat a missing signal more harshly than a refusal.
Why it matters to you
Two separate things are riding on the same decision, and they fail differently. One platform can suspend the account, which is loud. The other quietly stops counting, which is not, and shows up as a performance problem that no amount of campaign work will fix. Anyone reporting a sudden unexplained drop in conversions should be asked about the consent setup before anything else is changed.
What to ask or check
- 01Are consent signals actually reaching the ad platforms, or does the banner only control the site's own cookies?
- 02If Microsoft advertising is running, is consent mode or the framework in place, and definitely not both?
- 03Did conversions fall at the same moment the banner changed, and was anyone told to expect that?
What people get wrong
That the cookie banner is a legal formality with no effect on reporting. Microsoft states that without a consent signal it stops tracking tag-based conversions and stops populating remarketing lists.
Red flags
- A banner that governs the site's own cookies but passes nothing to the ad platforms.
- Both consent mode and the framework implemented at once, which Microsoft says never to do.
- A conversion drop investigated as a campaign problem when the banner changed the same week.
Who owns it
You do, contractually. Google puts the duty on the advertiser, including keeping records of consent and giving people a way to revoke it, and reserves the right to suspend or terminate for failure.
Where you will see it
In the tag setup behind your site, and in the month-on-month conversion figures right after a banner change.