If you manage day-to-day operations at a small firm, someone has probably told you that Microsoft 365 Business Premium handles your cybersecurity. That claim is partly true and partly a problem.
Business Premium is the strongest security tier Microsoft offers below enterprise pricing. For a firm of ten people or fewer running on Windows, it covers more ground than most small businesses have historically deployed. But it is not a complete security program. It has five specific gaps that leave a law firm, medical practice, or financial advisory exposed — gaps that are easy to overlook because the subscription looks, on paper, like it does everything.
The short answer: Microsoft 365 Business Premium delivers a meaningful baseline of endpoint protection, identity controls, and cloud security tools — but it does not back up your data, monitor your environment around the clock, or train your employees to recognize attacks. Closing those gaps requires additional tools and, for most small firms, outside help.
What Business Premium actually gives you
Start with what is genuinely there. Business Premium bundles several security layers that, until recently, only larger organizations could afford or staff:
- Microsoft Defender for Business — Endpoint protection with detection and response capabilities on Windows, Mac, iOS, and Android devices enrolled in the plan.
- Microsoft Intune — Device management that lets you enforce policies across company and personal devices: require a PIN, encrypt storage, wipe remotely if a device is lost.
- Entra ID (formerly Azure AD) Premium P1 — Multi-factor authentication, Conditional Access policies, and sign-in risk controls. This is the backbone of identity security in the Microsoft stack.
- Microsoft Defender for Office 365 Plan 1 — Safe Links and Safe Attachments scan URLs and email attachments before they reach the inbox. Anti-phishing policies add a layer against domain spoofing.
- Azure Information Protection — Sensitivity labels and encryption for documents and emails, useful for firms handling regulated data.
For a firm running entirely in the Microsoft cloud — email, files, Teams — that stack addresses a real range of threats. It is a legitimate security floor. The problem is what the floor does not cover.
The 5 gaps Business Premium leaves open
1. Your Microsoft 365 data is not backed up
This surprises most office managers. Microsoft maintains its infrastructure reliably, but infrastructure redundancy is not the same as a backup you can restore from. If ransomware corrupts a SharePoint library, an employee permanently deletes a folder, or a misconfigured retention policy quietly purges records, Microsoft's default tools may not recover what you need. Retention policies preserve data for compliance — they are not designed for operational recovery. A third-party backup solution that takes daily snapshots of Exchange, SharePoint, OneDrive, and Teams is the fix.
2. Sophisticated phishing still gets through
Defender for Office 365 Plan 1 stops known threats and performs basic impersonation checks. It does not include the advanced threat hunting or AI-driven impersonation detection found in Plan 2. Business email compromise — where an attacker impersonates your managing partner or a trusted vendor — is the pattern that most reliably bypasses Plan 1 controls. A third-party email security gateway or selective mailbox upgrades for high-risk users closes this gap.
3. Nobody is watching the alerts
Defender for Business generates endpoint alerts. Entra ID logs suspicious sign-ins. But those alerts appear in dashboards that someone must actively monitor. A small firm without a dedicated IT security person has no one doing that. The alerts accumulate, unread, until an incident forces the issue. Managed detection and response — a service where a dedicated team monitors your environment and responds to threats — is what fills this role.
4. Your employees are the largest attack surface
Business Premium does not include a security awareness training program at this tier. Phishing simulations, targeted training on credential attacks, and periodic testing of staff behavior are not part of the subscription. In a firm of ten people, one employee clicking a malicious link is a company-wide event. A structured training program — run quarterly at minimum — is a separate purchase and a separate discipline.
5. No security monitoring outside the Microsoft cloud
Business Premium secures the Microsoft cloud environment well. It does not provide centralized logging and alerting across other systems — a firewall, a cloud fax service, a practice management platform, or anything running on-premises. If your firm uses software outside the Microsoft stack, no one is correlating those logs. A managed security monitoring service that covers your full environment addresses this.