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Set up multifactor authentication for Microsoft 365

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Multifactor authentication means you and your employees must provide more than one way to sign in to Microsoft 365 is one of the easiest ways to secure your business. Based on your understanding of multifactor authentication (MFA) and its support in Microsoft 365, it's time to set it up and roll it out to your organization.

Multifactor authentication (MFA) is a very important first step in securing your organization. Microsoft 365 for Business gives you the option to use security defaults or Conditional Access policies to turn on MFA for your admins and user accounts. For most organizations, Security defaults offer a good level of sign-in security. But if your organization must meet more stringent requirements, you can use Conditional Access policies instead.

Important

If you purchased your subscription or trial after October 21, 2019, and you're prompted for MFA when you sign in, security defaults have been automatically enabled for your subscription.

Tip

If you need help with the steps in this topic, consider working with a Microsoft small business specialist. With Business Assist, you and your employees get around-the-clock access to small business specialists as you grow your business, from onboarding to everyday use.

Watch: Turn on multifactor authentication

Check out this video and others on our YouTube channel.

  1. Sign in to the Microsoft Entra admin center as least a Security Administrator.
  2. Browse to Identity > Overview > Properties.
  3. Select Manage security defaults.
  4. Set Security defaults to Enabled.
  5. Select Save.

Before you begin

Turn off legacy per-user MFA

Per-user MFA is a legacy service and you should give consideration to using the newer Security defaults or Conditional Access policies.

If you've previously turned on per-user MFA, you must turn it off before enabling Security defaults. You should also turn off per-user MFA after you've configure your policies and settings in Conditional Access.

  1. In the Microsoft 365 admin center, in the left nav choose Users > Active users.
  2. On the Active users page, choose multifactor authentication.
  3. On the multifactor authentication page, select each user and set their multifactor authentication status to Disabled.

Turn Security defaults on or off

For most organizations, Security defaults offer a good level of additional sign-in security. For more information, see What are security defaults?

If your subscription is new, Security defaults might already be turned on for you automatically.

You enable or disable security defaults from the Properties pane in the Microsoft Entra admin center.

  1. Sign in to the Microsoft Entra admin center as least a Security Administrator.
  2. Browse to Identity > Overview > Properties.
  3. Select Manage security defaults.
  4. Set Security defaults to Disabled (not recommended).
  5. Select Save.

Use Conditional Access policies

If your organization has more granular sign-in security needs, Conditional Access policies can offer you more control. Conditional Access lets you create and define policies that react to sign in events and request additional actions before a user is granted access to an application or service.

Important

Do not forget to disable per-user MFA after you have enabled Conditional Access policies. This is important as it will result in inconsistent user experience.

Conditional Access is available for customers who have purchased Microsoft Entra ID P1, or licenses that include this, such as Microsoft 365 Business Premium, and Microsoft 365 E3. For more information, see create a Conditional Access policy.

Risk-based conditional access is available through Microsoft Entra ID P2 license, or licenses that include this, such as Microsoft 365 E5. For more information, see risk-based Conditional Access.

For more information about the Microsoft Entra ID P1 and P2, see Microsoft Entra pricing.

Turn on Modern authentication for your organization

For most subscriptions modern authentication is automatically turned on, but if you purchased your subscription before August 2017, it's likely that you'll need to turn on Modern Authentication in order to get features like multifactor authentication to work in Windows clients like Outlook.

  1. In the Microsoft 365 admin center, in the left nav choose Settings > Org settings.
  2. Under the Services tab, choose Modern authentication, and in the Modern authentication pane, make sure Enable Modern authentication is selected. Choose Save changes.

Next steps - Send to your users

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