Google Ads Consent Mode v2: What Your Agency Is Not Telling You

The Compliance Deadline Has Passed

Since March 2024, Google has required Consent Mode v2 for any advertiser using Google Ads in the EEA and UK. If you are running ads without it, you are losing data. If your agency has not raised this, that is a red flag.

What Consent Mode v2 Actually Does

Consent Mode controls how Google tags behave based on user consent choices. When a user declines cookies, traditional tracking stops entirely. Consent Mode v2 instead sends "cookieless pings" that allow Google to model conversions without storing personal data.

There are two implementation levels:

Basic: Tags are blocked entirely until consent is given. Simple but you lose all data from non-consenting users.

Advanced: Tags fire in a restricted mode, sending anonymised pings. Google uses these to model the conversions you would have seen. This is where the real value sits.

The Data You Are Losing

In the UK, consent rates typically range from 40% to 70% depending on your consent banner design and audience. That means 30% to 60% of your conversion data is invisible to Google Ads.

Without Consent Mode v2 Advanced, Smart Bidding is optimising on partial data. It cannot see a significant chunk of your conversions, which means:

• Bid strategies undervalue high-performing keywords
• Budget allocation skews toward audiences that consent more readily
• Your reported ROAS understates actual performance
• Campaign optimisation decisions are based on incomplete information

What Modelled Conversions Mean for Your Account

Google's modelling fills the gap by estimating conversions from non-consenting users based on patterns from consenting ones. This is not guesswork. It is statistical modelling using aggregated, anonymised signals.

But it introduces uncertainty. Modelled conversions are estimates, not observed events. Your agency should be transparent about what percentage of your reported conversions are modelled versus observed.

If they are not distinguishing between the two, they are presenting estimates as facts.

The Implementation Reality

Proper Consent Mode v2 implementation requires:

1. A Google-certified Consent Management Platform (CMP)
2. Correct integration with Google Tag Manager or gtag.js
3. Two new parameters: ad_user_data and ad_personalisation
4. Testing to verify consent signals fire correctly
5. Monitoring to ensure modelled conversion rates are reasonable

This is not a five-minute job. And getting it wrong can mean either losing data unnecessarily or, worse, non-compliance with privacy regulations.

What to Ask Your Agency

1. Have you implemented Consent Mode v2 Advanced on our account?
2. What percentage of our conversions are modelled versus observed?
3. How has our consent rate changed over the last six months?
4. Have you optimised our consent banner for conversion rate?
5. How are you adjusting bid strategies to account for modelled data?

If they cannot answer these questions clearly, your account is flying on partial data and you do not even know it.