---
title: MediaMath Cookie Matching Service Tag Setup Guide
description: This article describes how to set up the MediaMath Cookie Matching Service tag.
url: https://docs.tealium.com/client-side-tags/mediamath-cookie-matching-service-tag/
---

<blockquote>
When using this tag with `utag` version 4.50 or later, you must set the `utag.js` [`always_set_v_id` setting](https://docs.tealium.com/platforms/javascript/settings/#always_set_v_id) to `true`. This setting ensures that the visitor ID is available for cookie synchronization. For more information, see the [utag 4.50 release notes](https://docs.tealium.com/platforms/javascript/version-4-50/#updating-to-version-450-or-later) and [Considerations for tealium_visitor_id when upgrading to utag 4.50+](https://support.tealiumiq.com/en/support/solutions/articles/36000535887-considerations-for-tealium-visitor-id-when-upgrading-to-utag-4-50-).
</blockquote>


## Tag Tips

* Sends the following server-side attribute back to Tealium:
  * `mediamathid`

## Tag Configuration

First, go to Tealium's tag marketplace and add the MediaMath Cookie Matching Service tag (Learn more about [how to add a tag](https://docs.tealium.com/manage-tags/)).

After adding the tag, configure the following settings:

* **Tealium Account**
  * (Optional) Your Tealium account

* **Tealium Profile**
  * (Optional) Your Tealium profile.

## Data Mappings

Mapping is the process of sending data from a [data layer variable](https://docs.tealium.com/data-layer-variables/) to the corresponding destination variable of the vendor tag. For instructions on how to map a variable to a tag destination, see [Data Mappings](https://docs.tealium.com/iq-tag-management/data-mappings/manage/).

The available categories are:

### Standard

|Variable| Description|
|---| ---|
|`tealium_account`| Tealium Account|
|`tealium_profile`| Tealium Profile|