---
title: "Master Customer ID"
date: "2025-12-09T10:56:50+00:00"
summary:
image:
type: "page"
url: "/customer-data-platform/master-customer-id"
id: "a1b17ec4-4eea-4821-bad3-0742288138fa"
---

CDP uses a default feature to group all records that do not have a valid Source Customer Number (SCN) associated with the Transaction entity. This group is identified by a Master Customer ID (MCID) of **\-1**, which represents unidentified customers.

You can choose to filter out these unidentified customers from various modules within CDP to focus the analysis and campaigns on identified customers.

Capabilities
------------

MasterCustomer ID (MCID) enables the following features:

*   **Unify customer profiles**: Automatically group and merge duplicate or fragmented identities into a single customer profile. For example, identities from different emails or devices.
    
*   **Provide a stable key for analytics and activation**: Use MCID as the only identifier in **Metrics**, **Audiences**, and **Campaigns** to ensure that counts and performance metrics reflect real people and not partial records.
    
*   **Reduce Unidentified records**: Apply identity resolution and standardization rules so that anonymous or partially known events are tied back to a known MCID wherever possible.
    

Filtering unidentified customers in metrics
-------------------------------------------

1.  [Sign in to your CDP user interface](https://docs.acquia.com/customer-data-platform/getting-started/signin-cdp).
2.  Click **Analytics** > **Metrics**.
3.  Select the **Customer Buyer Identification** dimension.
4.  Add this dimension as a filter and select **Identified** to include only identified customers in your report.

The **Buyer Identification** dimension indicates if a customer is identified or unidentified. Transactions with a blank or null customer value are attributed to the generic **Unidentified** customer, which has a Buyer Identification value of **\-1**. For more information, refer to [Creating Looks](/customer-data-platform/creating-looks "Creating Looks").

Filtering unidentified customers in campaigns
---------------------------------------------

1.  [Sign in to your CDP user interface](https://docs.acquia.com/customer-data-platform/getting-started/signin-cdp).
2.  Select **Actions** > **Campaigns+**.
3.  Add a filter for the **Buyer Identification** dimension and set it to **not equal** to **Unidentified**.

This excludes any unidentified customers from the audience and ensures campaigns and segments target only identified customers.

Note

If the **Buyer Identification** dimension is not currently surfaced in the Campaigns module's Configuration UI, contact [Acquia support](/service-offerings/contacting-acquia-support "Contacting Acquia Support") .