About User ID remarketing

You can create User ID remarketing lists by uploading customer segments keyed on custom generated user IDs. These user ID lists are eligible for targeting across Google properties, including Search, Shopping and YouTube.


Here are some of the benefits of using User ID lists for remarketing:

  • Advantages over Customer Match
    • User ID remarketing lists increase targeting coverage to signed-out traffic for Search and YouTube.
  • Advantages over RLSA
    • Offline segmentation: Savvy advertisers have robust offline backend systems to build highly tailored segments from their CRM data. These segments utilise both historic and dynamic attributes, which can’t always be passed via the RLSA pings. 
    • Post-facto state management: RLSA is dependent on page views to drive list changes. Therefore, targeting newly identified customer segments would require the user to visit the advertiser website first (in order to be added to a new RLSA list).

How User ID remarketing works

To implement a User ID remarketing list, add a top-level parameter called 'user_id' to your remarketing tag (this value is non-PII). User_id is a unique identifier that you internally associate with a certain customer. When that customer visits your website, the gTag javascript embedded in the website passes the user_id to Google, enabling Google to associate the given 'user_id' with the user’s Google cookies. This association lets you build User ID remarketing lists by uploading lists of user_ids via the Google Ads UI or API. 

Set up the User ID parameter in your remarketing tag

  1. Sign in to your Google Ads account.
  2. Click the tools icon  in the top right-hand corner of your account. 
  3. Under 'Shared library', click Audience manager
  4. Click Audience sources from the page menu. 
  5. Click the 3-dot icon 3 dot icon next to 'Google Ads tag'. 
  6. Click Edit source to set up a Google Ads tag. 
  7. Click Advanced settings then select the 'user_id' tick box. The user_id tick box may be greyed out if you're not on the Customer Match whitelist. Learn more
  8. Click Save and continue.
  9. If you haven't already installed the gtag.js global site tag on your site, follow these instructions to implement it.
  10. Implement the event snippet to pass the user_id parameter when users log in or register on your website (or on any page where you have access to a stable user_id for the current user). See additional instructions below.

You're responsible for generating user_id values for every user and ensuring that those values are stable and consistent for each user across sessions, browsers and devices.

Usually, this can be achieved if your website offers a user account functionality letting users register and sign in. Upon registration, you should generate a unique identifier for the user and pass it to Google Ads via the tag. When the same user comes back to your site and signs in again, you should pass the same identifier again via the user_id parameter.

An example of a way to pass the user_id parameter via gtag.js is shown below:

<script>gtag('event', 'login', { 'user_id': '132456' });</script>

The sample snippet above uses “login” as event name, but you can pass any event name that you want. The only requirement is to include 'user_id' as part of the event data argument.

Note that if you've already implemented the event snippet on certain pages of your site (for instance, to capture dynamic remarketing parameters), you may add the user_id parameter to your existing event snippets, as shown here:


  gtag('event', 'page_view', {

    'send_to': 'AW-CONVERSION_ID',

    'user_id': 'replace with value',

    'value': 'replace with value',

    'items': [{

      'id': 'replace with value',

      'google_business_vertical': 'retail'





When assigning user IDs, there are three important things to remember:

  1. Each user must have a unique user ID.
  2. For each user, the user_id parameter must be the same each time that they visit your website. For example, if Mary visits your website in the morning and you upload the user_id to create User ID remarketing lists via the Google Ads upload API, you must provide the same user_id for both cases.
  3. You may not pass Google personally identifiable information (PII) in the user_id

Upload 'user_ids' data using the Google Ads API (AdWords API)

Account owners or administrators can use the Google Ads API (AdWords API) to upload data files of 'user_ids' and manage their User ID remarketing audiences. Advertisers can upload a data file, add or remove customer data or edit configurations through the API. To learn more, visit the remarketing section of the Google Ads API (AdWords API) in the Google Developers website.
User ID data isn't considered PII data, and it's strongly recommended that advertisers hash User ID data before uploading to Google. Make sure that User IDs uploaded are identical to those sent to Google in the remarketing tag.

The user_id parameter can also be used for Google Ads cross-device linking. Note that if you set up user ID remarketing before 3 October 2018, you're already opted in to cross-device linking. Learn more about Advertiser cross-device linking.

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