Microsoft 365 Pricing, Licensing, and Support
Plans and buying
Microsoft 365 licensing is seat-based and subscription-based. Business plans (Basic, Standard, Premium) cap at 300 seats. Enterprise plans (E3, E5) have no seat cap and add compliance, analytics, and advanced security. E3 is the core productivity plus management bundle; E5 adds advanced identity (P2), endpoint, identity, and cloud-app defense, and advanced Purview. Add-ons exist, such as Defender for Office 365 P2, Entra ID P2, and extra storage. Buying routes include direct web purchase, Cloud Solution Provider (CSP) partners, and volume licensing for larger organizations. Monthly versus annual commitment changes price and flexibility; annual commitment usually lowers the per-user price.
Traps
Business Premium is frequently the right answer for small organizations that need security without E3. E3-versus-E5 questions hinge on P2 identity features and advanced compliance, not on whether Office apps are included. Self-service purchases and trials can create unmanaged licenses, so admins should review them in the admin center. Support is layered: included support through the admin center, Service Health for outage visibility, FastTrack for deployment guidance, and Premier or Unified support as paid options. SLA credits usually require a support request; do not assume automatic refunds.
Worked example
An organization with 450 users needs desktop Office, email, Teams, Conditional Access, and advanced eDiscovery. E5 fits: the seat count exceeds the 300-seat Business cap, and advanced eDiscovery is an E5 capability.
Rule of thumb: count seats first. Under 300 points to Business plans; above 300 points to Enterprise. Then match the specific feature-P2 identity, advanced compliance-to E3 or E5.