Microsoft 365 E3 vs E5 — An Enterprise Decision Guide
Licensing When you license Microsoft 365 for a 300+ user or heavily regulated organisation, three main SKUs come up: M365 E3, M365 E5 and the lower-segment Office 365 E3/E5. This article explains the real differences between Microsoft 365 E3 and E5, which of the five extra layers E5 brings actually pay off, and when migrating from E3 to E5 is the right call — grounded in Microsoft’s official documentation.
When are Enterprise plans needed?
The Microsoft 365 Business family caps at 300 users. Above that — or close to it with growth expected — you move to Enterprise (E3/E5). Microsoft’s Enterprise plans page defines the two main SKUs — E3 and E5 — alongside F1/F3 for frontline workers.
The real difference between E3 and E5
E5 = E3 + five additional product layers. Microsoft’s Enterprise plans comparison breaks it down. Summary:
| Category | Included in E3 | Added on E5 |
|---|---|---|
| Office apps (Word, Excel, PowerPoint, Outlook) | ✓ | ✓ |
| Exchange Online 100 GB + Teams + SharePoint + OneDrive | ✓ | ✓ |
| Windows 11 Enterprise | ✓ | ✓ |
| Microsoft Entra ID Plan 1 | ✓ | upgraded to Plan 2 |
| Microsoft Intune | ✓ | ✓ |
| Defender for Endpoint Plan 1 | ✓ | upgraded to Plan 2 |
| Defender for Office 365 | Plan 1 (add-on) | Plan 2 included |
| Defender for Identity | ✗ | ✓ |
| Defender for Cloud Apps | ✗ | ✓ |
| Microsoft Purview Information Protection P1 | ✓ | upgraded to P2 |
| Microsoft Purview Suite (advanced DLP + Insider Risk + eDiscovery Premium + Records + Communication Compliance) | ✗ | ✓ |
| Teams Phone | ✗ | ✓ (PSTN extra) |
| Power BI Pro | ✗ | ✓ |
| Microsoft Entra ID Plan 2 (PIM, Identity Protection) | ✗ | ✓ |
The five differentiators of E5:
- Defender XDR expansion: Endpoint P1 → P2, Office 365 P2 included, Identity and Cloud Apps added — four Defender products correlate as Defender XDR.
- Purview Suite: advanced DLP, Insider Risk Management, eDiscovery Premium, Records Management, Communication Compliance.
- Teams Phone: PBX capability over Microsoft 365.
- Power BI Pro: data analytics for every user.
- Entra ID P2: Privileged Identity Management, Identity Protection, risk-based policies.
The real question: which of these five do you actually need?
A quick read on each layer
1) Defender XDR. Critical for high-threat profiles (finance, defence, critical infrastructure, healthcare), APT targets, hybrid AD + cloud identity. Excessive if a third-party SIEM/SOC already covers it.
2) Purview Suite. Critical for organisations with heavy retention obligations under KVKK/GDPR; law firms (professional confidentiality + data protection); finance and healthcare (special-category data); proactive insider-risk management. Excessive for SMBs without compliance pressure.
3) Teams Phone. Critical when an aging PBX needs replacement, when contact-centre integration is planned, or when remote teams need landline numbers. Excessive when an existing PBX is new and stays.
4) Power BI Pro. Critical for data-driven companies pushing dashboards across finance, sales, marketing and operations. Excessive when only 15–20 users use Power BI — buy them Pro licences separately instead of E5 for everyone.
5) Entra ID P2. Critical when admin counts are high, KVKK + ISO 27001 strict alignment, supply-chain attacks pushing least-privilege. Excessive if admin count is small and manageable manually.
Decision matrix
| Organisation profile | Recommended |
|---|---|
| 300–1,000 users, standard sector, existing SIEM/SOC | M365 E3 + add-ons as needed |
| Finance, healthcare, public sector — high threat + heavy compliance | M365 E5 |
| Law firm — professional confidentiality + eDiscovery need | M365 E3 + Purview add-on, or direct E5 |
| Power BI used broadly (300+ users with 100+ Pro users) | M365 E5 |
| PBX up for replacement, Teams Phone target | M365 E5 + Calling Plan or Direct Routing |
| Want Defender XDR single-pane visibility | M365 E5 |
| Third-party SOC/SIEM in place, won’t use Defender layers | M365 E3 |
| 5,000+ users, mixed needs | E3 baseline + E5 add-ons for critical admins |
Mixed-SKU approach — E5 isn’t for everyone
Microsoft allows mixed SKUs within the same tenant. Practical strategy:
- General users (operations, production support, admin staff) → M365 E3
- IT admins, DPO, legal, executives, finance → M365 E5 or E5 Security/Compliance add-ons
- Field staff → M365 F1/F3
This mix typically reduces total cost by 15–30% (based on Microsoft list price; actual savings vary by organisation profile). Use the Microsoft 365 Admin Center License Usage report + department-level access analysis to size the mix.
How to TCO E5 properly
Answer three questions:
- Total spend on external security tools today: third-party AV/EDR + CASB + DLP + IAM + Power BI Pro + PBX + eDiscovery — annual aggregate.
- Overlap during migration: when existing contracts end, double-billing windows.
- Configuration cost: consulting + internal team training to actually configure Defender XDR, Purview Suite, PIM, Teams Phone.
If (1) > (E5 − E3 delta), E5 is economically rational — provided you actually configure the layers you’re paying for.
Frequent confusions
Does buying E5 mean I’m automatically protected? No. Licence ≠ configuration. Defender, Purview and PIM all require deliberate deployment. Unconfigured E5 leaves capacity unused — the most common waste.
Are Office 365 E5 and Microsoft 365 E5 the same? No. Office 365 E5 does not include Defender Suite + Entra P2 + Windows Enterprise + Intune. Mixing them up is expensive.
Is E5 required to use Teams Phone? No. Teams Phone can be added as an add-on to E3. It’s just included in E5 by default.
Practical recommendation
For most mid-to-large organisations the right starting point is M365 E3. The move to E5 can come later, driven by specific needs — particularly via the E5 Security / E5 Compliance add-ons that let you phase the transition.
We provide a free E3 vs E5 TCO analysis and mixed-SKU optimisation review. Details on the Microsoft 365 service page or contact us directly.
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