GA4 Attribution Update 2025

• Introduction
• GA4 Attribution Challenges & Mitigation Steps Implemented in 2024
  • (A) Misattribution of Google Paid campaigns to Organic
  • (B) (not set) in reporting
  • (C) Overattribution to Direct
• Mitigation Steps in 2025
  • Aggregated Identifiers
  • New Data Labels
  • New Diagnostic Tools in UI

Traffic attribution is one of the most important features of analytics platforms such as GA4.

However, due to multiple factors including:

• Increased browser tracking prevention, resulting in loss of data signals (e.g. degradation of URL parameters and third-party cookies)
• Privacy regulation, preventing some tracking techniques to be used

There have been some challenges in achieving the most accurate attribution results.

In this article, we will explain:

• The attribution challenges in GA4 and the mitigation steps that have been implemented in 2024
• The additional mitigation steps that will be implemented in 2025

The attribution challenges faced in GA4 can be grouped into three pillars:

• (A) Misattribution of Google Paid campaigns to Organic
• (B) (not set) in reporting
• (C) Overattribution to Direct

When you perform a search on Google, you will often see that the top links have a "Sponsored" label. For example:

These are considered "Paid Search" as companies pay money for their links to be listed on top. This is also known as Cost per Click (cpc).

When you click on a paid link, Google automatically adds a unique ad identifier (gclid/dclid) to URL parameter of the landing page. For example:

https://www.mywebsite.com would become https://www.mywebsite.com?gclid=xxXXxxxXXxx

On the landing page, GA4 will read this value and automatically convert it into proper traffic source dimensions. For example:

source / medium = google / cpc

Back to the Google search result page, when you scroll farther down, you will see links without the "Sponsored" label. For example:

These are considered "Organic Search". In order for your links to be ranked high, you need to ensure that your website has good SEO. For example, ensure that your website has good content that is relevant to what users are searching for. You do not need to pay extra money for organic ranking.

For organic links, Google does not add any additional URL parameter.

Keep in mind that both link clicks happen on the same source website - www.google.com. That means that, on the landing website, the only indicator that the traffic source is paid or organic is the gclid URL parameter.

To illustrate:

Now here's the issue. Due to privacy regulation, if users do not consent to advertising (eg. ad_user_data flag is denied), the gclid URL parameter (which is unique to a user) cannot be used by Google.

That means, in cases like this, GA4 has no way of telling if the traffic source is Paid or Organic. Since it can only read that the source website is www.google.com, it can only set the traffic source to Organic. This is the reason for: Misattribution of Google Paid campaigns to Organic.

In 2024, Google has implemented several signal-gathering improvements to reduce this issue. However, the main challenge remains - If the auto ad identifier cannot be used, there's no clear indicator to tell if the traffic source is Paid or Organic. Read to find out how Google intend to solve this in 2025.

(not set) value in GA4 can be due to many factors, one of which is when GA4 events are fired before the config command (eg. Google Tag).

For example, if you have a firing sequence like this:

In 2024, Google made a change in that all GA4 events are deferred until after the config command has been run. You should no longer see this (not set) issue resulting from the

less-than-ideal firing sequence. Nevertheless, we always recommend to fire the config command as priority before any other event tags. For example, it is recommended that you fire all Google Tags on GTM Initialization - All Pages event trigger.

It takes time for GA4 to process the vast amount of data. This is especially true when it needs to connect to multiple ad platforms to reconcile the data. While GA4 is processing data, the traffic source dimensions can be temporarily set to empty which is equivalent to Direct channel.

That means, if you look at today or yesterday's data (which could still be processing) in GA4, you could see a higher percentage of Direct traffic source. This is the reason for: Overattribution to Direct.

Read on to learn how Google intend to reduce this confusion in 2025.

Addresses: (A) Misattribution of Google Paid campaigns to Organic

We should all be familiar with:

• Auto tagging
  Where the automatic gclid/dclid URL parameters are added to the landing page URLs. This has been the recommended method as it is automatic, speeding up your ad campaign workflow. However, as mentioned above, due to the fact that this identifier is unique to a user, it cannot be used when the users do not consent to advertising.
• Manual tagging
  Where you manually add the UTM parameters to your landing page URLs. This method doesn't have the same consent issue because these are campaign parameters, they are not unique to a single user. However, this method requires manual work and mistakes are often made when manually adding the parameters to URLs.

As of now, when both methods are used, auto tagging takes priority over the manual tagging method.

In 2025, Google will be changing this to a waterfall logic and adding a new tagging method in between:

1. Auto tagging - Ad Identifiers
   ‍This remains the same, using gclid/dclid URL parameters.
2. Auto tagging - Aggregate Identifiers *new*
   ‍If the ad identifier above cannot be used (eg. when consent is not granted), GA will fallback to this new method. It works automatically just like the ad identifier, however, it is an aggregated campaign identifier and it's not unique to a user. It is basically a combination of auto- and manual-tagging.
3. Manual tagging - UTM parameters
   ‍Lastly, if the two identifiers above are not available, GA will fallback to the manual UTM parameters.

Google will be launching this in early 2025. Do stay tuned for more official information and the recommendations for manually adding UTM parameters to your landing URLs as a fallback safety net.

Addresses:

• (A) Misattribution of Google Paid campaigns to Organic
• (C) Overattribution to Direct

Google will be making two changes to the traffic source data in 2025:

1. When data is still being processed, instead of defaulting the traffic source dimensions to empty (=Direct), GA4 will now show (data not available). This should help to avoid confusions about (C) Overattribution to Direct.
2. When ad identifiers cannot be used, instead of defaulting the traffic source dimension to Organic, GA4 will now show (not set). This should reduce the issue of (A) Misattribution of Google Paid campaigns to Organic. Although in our opinion, the (not set) value can cause a different confusion, but this is better than before.

Google will also be launching many diagnostic tools in the GA4 UI to improve clarity and to help identify potential tracking issues early. You will start to see these diagnostic messages in 2025.

These includes:

• (data not available) diagnostic
  ‍Indicates that the data is still being processed.
• (not set) diagnostic
  ‍Indicates when there is a potential issue that we may need to fix.
• Missing session_start event
  Indicates when there is a potential consent mode implementation issue.
• Missing UTM parameter
  ‍Indicates when improved UTM coverage can be used to address a high volume of (not set) values.
• Spammy user-ID
  Indicates a potential misconfiguration of User-ID tracking which could result in overattribution to Direct.
• System generated annotations
  A timeline view to inform users about data impacting events.

Do stay tuned for more official information to be announced.

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