Set up Advertiser cross-device linking

Use the power of your user data to show your Display ads to your users across their devices.

This article explains how to set up the user_id custom parameter in your remarketing tag to enable Advertiser cross-device linking. Note that if you set up user ID remarketing before October 3rd, 2018, you already are opted in to cross-device linking.

Before you begin

The user_id parameter is a unique, anonymous identifier that you should generate and send via the Google Ads remarketing tag that links different devices and browsers for a single user. Learn more About cross-device linking with user ID parameters.

If you're setting up Advertiser cross-device linking, you need to comply with the Advertiser cross-device linking policy. Unless you set up cross-device linking before October 3rd, 2018, you’ll need to contact your Google sales manager to whitelist your account for cross-device linking.


Set up the cross-device parameter in your remarketing tag

  1. Sign in to your Google Ads account.
  2. Click the tools icon in the upper 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 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 checkbox. The user_id checkbox may be grayed out if you are not on the Customer Match whitelist. Learn More about Customer Match
  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 are 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 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 (or if they are automatically signed-in based on a persistent cookie you might set), 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': '123456' });</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 have 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 they visit your website. For example, if Mary visits your website in the morning and again later in the afternoon, and you upload the user_id to create Customer Match lists via Customer Match 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.

Opt-in to Advertiser cross-device linking

If you did not setup up cross-device linking before October 3rd, 2018 and would like to you'll need to contact your Google sales manager.

Note: Adding user_id parameter in your remarketing tag and sending user_id parameter values are not sufficient for enabling cross-device linking.

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