Security defaults or Conditional Access? Choosing sign-in protection for Microsoft 365

Multi-factor authentication (MFA) is one of the most effective ways to stop attackers who have stolen a password. Microsoft 365 offers two main ways to require it: security defaults and Conditional Access. Choosing between them depends on your licensing and how much control you need.

Security defaults

Security defaults are a free, preconfigured set of protections available in every Microsoft Entra ID tenant. When enabled, they require all users to register for MFA, require MFA for administrators, prompt users for MFA when Microsoft detects risk, and block older sign-in methods that can't support MFA.

The trade-off is that security defaults are all or nothing. You can't exclude a specific account, require MFA only outside the office, or apply different rules to different groups.

Conditional Access

Conditional Access lets you build policies around who is signing in, from where, on what device, and to which application. For example, you can require MFA for everyone, require a compliant company device to open email, and block sign-ins from countries where you don't do business.

Conditional Access requires Microsoft Entra ID P1 licensing, which is included in plans such as Microsoft 365 Business Premium. You also have to turn off security defaults before Conditional Access policies take over.

How to decide

• No MFA today: turn on security defaults now. It's far better than nothing and costs nothing.
• Business Premium or Entra ID P1 licenses: plan a move to Conditional Access, starting with policies that require MFA for all users and block legacy sign-in.
• Exceptions needed: if a shared mailbox, scanner, or service account breaks under security defaults, fix the underlying setup rather than leaving MFA off for everyone.

Before you switch anything on

Tell your team what's changing, help them install an authenticator app, and confirm you have at least one emergency administrator account that's protected and documented. A rushed rollout locks people out. A planned one usually goes unnoticed after the first sign-in.

Zach Albano

Founder of Albano Tech, providing managed IT, Microsoft 365, and cybersecurity services to businesses in Delaware, Maryland, and the Philadelphia region. More about Zach.