Microsoft Entra External ID - Securing Identities Beyond Your Organization

What is Microsoft Entra External ID?

Every organization faces the same challenge: how do you securely give people outside your company access to what they need, without creating a security headache or a frustrating user experience?

That is exactly the problem Microsoft Entra External ID is built to solve. It is Microsoft's next-generation Customer Identity and Access Management (CIAM) platform, unified under the Microsoft Entra umbrella. In plain terms, External ID lets you control how external users, whether they're business partners, vendors or end customers of your applications, authenticate and access your resources.

Think of it as a secure front door that you design and control. Visitors bring their own keys (their existing identities), and you decide what rooms they can enter.

The two core scenarios

External ID addresses two distinct but related problems. Understanding the difference is key to knowing which one applies to your situation.

Scenario 1: B2B Collaboration (business partners and guests)

If you need to give employees from another company (a vendor, a supplier, a consulting partner) access to your internal Microsoft 365 apps, SharePoint sites or line-of-business applications, B2B Collaboration is your answer.

Here's how it works in practice: imagine your organization is onboarding a new consulting firm. Instead of creating new accounts for each consultant in your Active Directory, you invite them using their existing corporate identities. They authenticate against their organization and then seamlessly access only what you've shared with them: Teams channels, SharePoint documents or internal tools.

Key capabilities

• Invite guests via the Microsoft Entra admin center or PowerShell using their existing work, school or social accounts
• Apply Conditional Access policies, including MFA and device compliance, just as you would for full-time employees
• Guest user objects are created in your directory so you can manage permissions and group memberships normally
• Integrate with Microsoft Teams shared channels so external collaborators work alongside your team without switching accounts
• Use Entitlement Management to automate access request workflows, reviews and expiration for external users at scale

Real-world example

A manufacturing company works with three logistics partners. Using B2B Collaboration, each partner's employees access a shared Teams workspace and a custom shipping dashboard using their own company credentials. The manufacturing company's IT team maintains full control over access policies, can enforce MFA and can revoke access at any time, all without managing passwords for external users.

Scenario 2: External Tenants (consumer and customer-facing apps)

If you're building or running applications that end customers use (a mobile banking app, a retail website, a healthcare patient portal), you need a different approach. This is where External ID's external tenant configuration comes in.

An external tenant is a separate Microsoft Entra tenant dedicated entirely to your customer-facing applications. It is kept completely separate from your employee directory, which is an important security and compliance boundary.

Key capabilities

• Let customers sign up and sign in using email/password, email one-time passcodes or social accounts like Google or Facebook
• Design a fully branded sign-in experience with your company's logo, colors and background images; no Microsoft branding required
• Collect custom attributes during sign-up such as name, postal code, loyalty number or job title
• Enforce MFA for additional security and apply risk-based adaptive access policies
• Analyze user activity and engagement data to support business decisions and drive growth

Real-world example

A retail company builds a loyalty app. Customers sign up using their Google account or email. The sign-in page looks like the company's own website. During registration, customers provide their rewards number and zip code. All of this data is captured in the external tenant, completely separate from the company's employee systems, and the app uses it to personalize the shopping experience.

How does this relate to Azure AD B2C?

This is a question that comes up often. Azure Active Directory B2C (Azure AD B2C) was Microsoft's previous dedicated CIAM solution. External ID is its successor, not just a rename.

External ID consolidates B2B and B2C capabilities into a single, unified platform under Microsoft Entra. The key benefits of moving to External ID include a simpler configuration model (no more complex custom policies), native integration with the broader Entra security and governance platform and a modern developer experience.

For existing Azure AD B2C customers: Microsoft has committed to supporting the service until at least May 2030, so there is no immediate urgency to migrate. [AUTHOR: Add source link for May 2030 support commitment] New Azure AD External Identities P1 and P2 plans are no longer available for purchase as of May 1, 2025, and new customers should start with External ID. [AUTHOR: Add source link for P1/P2 retirement date]

Built on the Microsoft Entra security foundation

One of the most compelling reasons to use External ID, rather than building your own identity system, is that it inherits the full security and compliance capabilities of Microsoft Entra. This matters whether you're managing business guests or millions of consumer accounts.

• Conditional Access: Apply risk-based policies that can require MFA, block sign-ins from unfamiliar locations or demand compliant devices for both internal and external users
• Identity Protection: Detect and respond to suspicious sign-in behavior automatically
• MFA Enforcement: Add a second layer of verification via email one-time passcodes
• Entitlement Management: Automate access request workflows, access reviews and expiration for external users at scale

Getting started: What does implementation look like?

For IT administrators and developers evaluating External ID, here is a high-level view of the implementation path for an external (customer-facing) tenant.

Step 1 – Create an external tenant

In the Microsoft Entra admin center, navigate to Identity > Overview > Manage tenants and create a new tenant, selecting the External configuration. You choose your geographic location and domain name. A 30-day free trial is available without an Azure subscription.

Step 2 – Register your application

Register your web or mobile app in the external tenant. This establishes a trust relationship between your application and External ID, providing you with the client ID and tenant details your app code needs.

Step 3 – Create a sign-in user flow

Define the end-to-end sign-up and sign-in experience. Choose your identity providers (email/password, one-time passcode, Google, Facebook), select the user attributes to collect and configure language and branding. Each external tenant supports up to 10 user flows.

Step 4 – Customize and secure

Apply your company branding, enable MFA, configure Conditional Access policies and optionally add custom authentication extensions to inject business logic into the sign-in flow (such as calling an external CRM or loyalty system during registration).

Pricing

External ID is priced on a Monthly Active User (MAU) model; you only pay for users who actually authenticate in a given month. [AUTHOR: Add source link for MAU pricing figures]

Table 1 - Pricing

Is External ID right for your organization?

Table 2 - Use Case Scenario

Summary

Microsoft Entra External ID unifies two long-standing identity challenges, managing business partners and managing app customers, into a single, modern platform. It removes the complexity of building and maintaining your own identity infrastructure, delivers enterprise-grade security out of the box and gives you the flexibility to create branded, seamless experiences for your users regardless of where their identity lives.

Whether you are an IT administrator looking to streamline partner access, a developer adding authentication to a new application or an architect evaluating your organization's CIAM strategy, External ID is worth understanding, because the question of "how do we securely manage who gets in" is not going away.