UPDATE 5/12/23:
We’ve documented this more thoroughly at:
https://learn.microsoft.com/en-us/azure/active-directory/authentication/concept-mfa-licensing#available-versions-of-azure-ad-multi-factor-authentication
ORIGINAL 12/26/2019:
At Ignite 2019, we announced free Azure Active Directory Multi-factor Authentication for all customers using the Microsoft Authenticator app – including those using Azure Active Directory Free.
Our top priority is to make it super easy for you to secure your Azure AD accounts. It’s the main reason we’ve invested so much in building our passwordless sign-in options like Windows Hello and the Microsoft Authenticator app.
To make it easy for everyone to adopt more secure and phishing-resistant authentication, today we announced that all customers can now enable MFA for free with the Microsoft Authenticator app. Starting later this month, MFA will be enabled as a security default in all new Azure Active Directory tenants for Microsoft 365, Office 365, Dynamics, and Azure. These news defaults will be rolling out gradually to new tenants over the next few months. Customers with more than 150 seats can also now contact Microsoft to set up MFA and security capabilities via FastTrack.
- SITE: Enable multi-factor authentication for free
https://www.microsoft.com/en-us/security/business/identity/mfa?rtc=1 - ANNOUNCEMENT: What’s new in Azure Active Directory at Microsoft Ignite 2019
https://techcommunity.microsoft.com/t5/Azure-Active-Directory-Identity/What-s-new-in-Azure-Active-Directory-at-Microsoft-Ignite-2019/ba-p/827831
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