Most enterprises running Microsoft 365 E5 are simultaneously paying for third-party tools that duplicate capabilities already included in their licence bundle. This advisory identifies the 8 most common overlap categories, provides a cost quantification framework, maps three strategic decision paths, and delivers a rationalisation playbook that typically saves 15–25% on combined Microsoft-plus-third-party software spend.
Enterprise organisations routinely maintain software portfolios that have grown organically over years. They accumulate through departmental purchases, M&A activity, vendor-driven upsells, and the natural tendency to add tools without retiring the ones they replace. When Microsoft 365 E5 enters this environment, the problem intensifies. E5 is the most feature-rich enterprise productivity bundle available, encompassing security, compliance, analytics, telephony, identity management, and collaboration capabilities that directly overlap with standalone products many organisations already own.
The financial impact of this redundancy is consistently underestimated. In our advisory practice across 500+ enterprise Microsoft engagements, we find that the typical organisation running M365 E5 maintains $500,000 to $3,000,000 annually in third-party software licences that duplicate capabilities already included in their Microsoft bundle. This is not a rounding error. It represents real budget that could be redirected toward strategic initiatives, reduced from the IT cost base entirely, or used as negotiation leverage to secure better terms from both Microsoft and third-party vendors.
The redundancy problem is structural, not accidental. Microsoft’s E5 bundle strategy is deliberately expansive. It includes capabilities across security, compliance, voice, analytics, and identity that were previously sold as separate products. Microsoft’s commercial incentive is to sell E5 as an all-inclusive platform and then encourage customers to consolidate onto Microsoft tools. But most enterprises purchased their third-party security, telephony, and analytics tools before upgrading to E5, and the legacy contracts persist alongside the new Microsoft bundle. This creates parallel spend that no one actively chose but everyone passively funds.
Software redundancy in Microsoft environments follows predictable patterns. The following eight categories represent the most frequent and financially significant overlaps we identify in enterprise environments.
| Category | Microsoft E5 Capability | Common Third-Party Duplicates | Overlap Risk | Typical Annual Waste (5,000 Users) |
|---|---|---|---|---|
| Endpoint Security | Defender for Endpoint (EDR/XDR) | CrowdStrike Falcon, SentinelOne, Carbon Black, Symantec/Broadcom | Critical | $300,000–$750,000 |
| Email Security | Defender for Office 365 (anti-phishing, safe links/attachments) | Proofpoint, Mimecast, Barracuda | Critical | $150,000–$400,000 |
| Telephony | Teams Phone System (cloud PBX, calling plans) | Cisco UCM/Webex Calling, Avaya, RingCentral, Zoom Phone | Critical | $400,000–$1,200,000 |
| Business Intelligence | Power BI Pro (included in E5) | Tableau, Qlik, Looker, MicroStrategy | High | $200,000–$600,000 |
| Cloud Storage | OneDrive for Business (1TB+), SharePoint Online | Box, Dropbox Business, Google Drive | High | $100,000–$350,000 |
| Identity & Access | Entra ID P2 (conditional access, PIM, identity protection) | Okta, Ping Identity, CyberArk (partial) | High | $150,000–$500,000 |
| Information Protection | Purview (DLP, sensitivity labels, eDiscovery Premium) | Symantec DLP, Digital Guardian, Forcepoint DLP | Medium | $100,000–$300,000 |
| Conferencing | Microsoft Teams (meetings, webinars, live events) | Zoom Meetings, Cisco Webex, GoTo Meeting | High | $75,000–$250,000 |
Endpoint Security: Microsoft Defender for Endpoint vs. CrowdStrike/SentinelOne/Symantec. This is the highest-value overlap in most enterprises. Dedicated endpoint detection and response (EDR) products from CrowdStrike, SentinelOne, and Carbon Black typically cost $40 to $80 per endpoint per year at enterprise scale. Microsoft Defender for Endpoint, included in E5, provides functionally comparable EDR capabilities including endpoint detection, automated investigation and remediation, threat analytics, and integration with Microsoft’s broader security stack (Defender for Identity, Defender for Cloud Apps, Microsoft Sentinel). In independent evaluations, including MITRE ATT&CK assessments, Defender for Endpoint now ranks alongside the leading dedicated EDR vendors. The key differentiation question is not whether Defender is “good enough” in general, but whether your specific security operations centre (SOC) has built workflows, custom detections, threat hunting playbooks, and SIEM integrations that depend on features unique to the incumbent EDR vendor. If the answer is “our SOC could operate effectively on Defender,” the redundancy cost of $300K to $750K annually for a 5,000-user organisation is difficult to justify.
Telephony: Teams Phone System vs. Cisco UCM/Avaya/RingCentral. Voice telephony is often the single largest redundancy by dollar value. Legacy PBX systems (Cisco Unified Communications Manager, Avaya) carry substantial ongoing maintenance and licensing costs of $150 to $300+ per user per year including hardware amortisation, trunk lines, and support contracts. Cloud PBX alternatives (RingCentral, Zoom Phone) are less expensive but still represent $120 to $200 per user annually. Microsoft Teams Phone System, included in E5, provides cloud PBX calling, auto-attendants, call queues, voicemail, and PSTN connectivity (via Calling Plans or Direct Routing). For organisations already on E5, the marginal cost of adopting Teams Phone is the PSTN connectivity, typically $8 to $15 per user per month for Calling Plans or the cost of a Session Border Controller for Direct Routing. The migration complexity is real (number porting, analog device handling, contact centre integration), but the financial case is compelling: eliminating a parallel telephony platform saves $400K to $1.2M annually at 5,000 users.
Email Security: Defender for Office 365 vs. Proofpoint/Mimecast. Many enterprises deployed Proofpoint or Mimecast when Microsoft’s native email security was insufficient. Microsoft Defender for Office 365 Plan 2 (included in E5) has since matured considerably, offering anti-phishing protection, safe attachments and links, automated investigation and response, attack simulation training, and threat explorer. For organisations that do not have specialised email threat requirements (financial services with advanced impersonation protection, organisations handling highly targeted nation-state threats), Defender for Office 365 now provides comprehensive email security. The annual cost of maintaining a parallel email security gateway is typically $30 to $80 per user ($150K to $400K for 5,000 users). Before consolidating, verify that your Defender configuration matches the policy granularity and reporting capabilities your security team requires.
Business Intelligence: Power BI Pro vs. Tableau/Qlik. Power BI Pro is included in every E5 licence. If you are also paying for Tableau or Qlik licences, you are funding two analytics platforms simultaneously. The decision here is more nuanced than security or telephony. Power BI excels at self-service analytics, Microsoft ecosystem integration (Excel, Teams, SharePoint, Dynamics), and cost-effective deployment across large user populations. Tableau provides superior data visualisation capabilities, more flexible data preparation, and stronger support for non-Microsoft data sources. The practical approach for most enterprises is to consolidate the majority of business users onto Power BI (eliminating 60 to 80% of Tableau licences) while retaining Tableau for specialist data analysts and teams with advanced visualisation requirements. This hybrid approach typically reduces BI licensing costs by 50 to 70%.
For a 5,000-user enterprise running M365 E5 with overlapping third-party tools in just four of these categories, the annual redundant spend typically ranges from $800,000 to $2,500,000. For 10,000+ user organisations with legacy contracts across most categories, we routinely identify $2M to $5M+ in annual redundant software spend. This money is funding duplicate capabilities that provide marginal incremental value over what is already included in the E5 licence you are paying for.
Before making rationalisation decisions, build a precise cost model that quantifies the redundancy in your specific environment. This framework prevents both over-consolidation (eliminating a tool that provides genuine unique value) and under-consolidation (leaving redundant spend in place because the magnitude is unclear).
Create a comprehensive catalogue of every software product in use across the eight overlap categories. For each product, document the annual licence cost (total and per-user), the number of active users, the contract term and renewal date, the specific capabilities used (not just the capabilities available), and the business processes or teams dependent on the tool. This inventory must include not just centrally procured enterprise software but also departmental purchases, SaaS subscriptions managed by individual business units, and shadow IT tools discovered through network monitoring or expense report analysis.
For each third-party tool identified, determine the specific M365 E5 feature that provides equivalent functionality. Assess the degree of overlap: does the Microsoft capability fully replace the third-party tool (100% overlap), partially replace it (50 to 80% overlap with some unique features in the third-party tool), or merely overlap in a narrow area (less than 50%)? This assessment requires technical input from the teams that use both tools. Marketing’s view of Tableau versus Power BI will be different from finance’s view, and both perspectives matter.
For each overlap, calculate the annual cost of maintaining the redundant capability. This includes the third-party licence cost for the overlapping functionality (not the entire contract if only part of the product overlaps), the internal support costs for maintaining two parallel tools (help desk, training, integration, administration), the user productivity cost of context-switching between two tools that serve similar purposes, and the opportunity cost of not fully leveraging the E5 investment. Sum these costs across all overlap categories to produce your total annual redundancy figure.
Present the redundancy cost as a percentage of your total Microsoft spend. In our experience, redundant third-party spend typically equals 20 to 40% of the E5 licence cost itself. Framing it this way gets executive attention: “We are paying $8M for M365 E5, and we are paying an additional $2.4M for third-party tools that duplicate what E5 already includes. That is a 30% hidden surcharge on our Microsoft investment.”
For each overlap category, one of three strategic paths will deliver the optimal outcome. The right choice depends on the specific category, the maturity of the Microsoft capability, and your organisation’s risk tolerance.
This path maximises the return on your E5 investment by fully adopting the Microsoft capability and eliminating the third-party tool. It is the right choice when the Microsoft capability meets or exceeds your functional requirements, when the switching cost (migration, retraining, integration changes) is manageable relative to the savings, when the organisation benefits from a unified platform (single pane of glass for security, integrated analytics, unified communications), and when the third-party contract is approaching renewal creating a natural exit point.
Cloud storage (OneDrive/SharePoint replacing Box/Dropbox), conferencing (Teams replacing Zoom/Webex for most use cases), basic BI (Power BI replacing Tableau for standard reporting), and email security (Defender for Office 365 replacing Proofpoint/Mimecast for organisations without highly specialised email threat requirements).
This path is appropriate when the third-party tool provides genuinely superior capability that Microsoft cannot match for your specific use case. Rather than paying for both, downgrade the Microsoft licence to remove the overlapping component. In practice, this often means moving affected users from E5 to E3 (which excludes the advanced security, compliance, and analytics components) and retaining the third-party tool that provides those capabilities.
Endpoint security (CrowdStrike or SentinelOne for organisations with mature security operations centres that depend on the third-party EDR’s specific detection capabilities and threat intelligence), advanced analytics (Tableau for organisations with complex visualisation and data preparation requirements that exceed Power BI’s capabilities), and identity management (Okta for organisations with complex multi-cloud identity federation requirements beyond Entra ID’s current capabilities).
The most common optimal strategy is a hybrid that assigns different licence profiles to different user populations based on their actual needs. Not every employee requires E5’s full feature set, and not every employee needs the third-party tool either. Segmenting your user base enables precise cost optimisation.
| User Segment | Count | Current (All E5) | Optimised Licence | Annual Cost | Annual Saving |
|---|---|---|---|---|---|
| Power users (security, compliance, analytics, telephony) | 3,000 | $2,052,000 | M365 E5 ($57/user/mo) | $2,052,000 | $0 |
| Standard knowledge workers (Office, email, Teams, OneDrive) | 5,000 | $3,420,000 | M365 E3 ($36/user/mo) | $2,160,000 | $1,260,000 |
| Frontline workers (basic productivity, shifts, mobile) | 2,000 | $1,368,000 | M365 F3 ($8/user/mo) | $192,000 | $1,176,000 |
| TOTAL | 10,000 | $6,840,000 | Mixed | $4,404,000 | $2,436,000/year |
In this scenario, moving from uniform E5 deployment to a segmented licence model saves $2.4M annually, a 36% reduction in Microsoft licence spend, without removing any capability that users actually need. The 5,000 E3 users retain full Office, Exchange, SharePoint, Teams, and OneDrive functionality. The 2,000 frontline workers retain mobile access, shifts, and basic communication. Only the 3,000 users who genuinely require E5’s advanced features continue at the premium tier. Additional savings from eliminating redundant third-party tools (security, telephony, storage) for the E5 segment can add another $500K to $1M annually.
Redress Compliance provides independent Microsoft licensing advisory. We help CIOs optimise M365 licence mix, eliminate redundant third-party tools, negotiate EA renewals, and implement governance frameworks that prevent future redundancy. Fixed-fee engagements with no Microsoft commercial relationship.
Microsoft Advisory Services →Your redundancy analysis is not just an internal cost-reduction tool. It is a powerful negotiation asset that can be deployed in three directions simultaneously.
Leverage with Microsoft. If your analysis reveals that significant E5 features are unused because third-party tools serve those functions, use this to negotiate better E5 pricing. The message to Microsoft is clear: “We are evaluating whether E5 delivers sufficient value over E3 given that we use [third-party tool] for [capability]. To justify maintaining E5, we need pricing that reflects the portion of the bundle we actually use.” This positions you for either a deeper E5 discount or a negotiated downgrade with selective add-ons. Additionally, if you commit to consolidating onto Microsoft tools (retiring third-party alternatives), use that commitment as leverage: “We will adopt Defender/Teams Phone/Power BI fully, which increases our E5 utilisation and Microsoft’s platform stickiness. This deserves recognition in pricing.”
Leverage with third-party vendors. If you decide to retain a third-party tool, use the Microsoft alternative as competitive pressure. Every third-party vendor in the overlap categories knows that Microsoft includes a competing capability in E5. Approaching Cisco, CrowdStrike, or Tableau with “we are evaluating whether Microsoft’s included capability can replace your product” creates genuine pricing pressure. Third-party vendors facing potential loss of an enterprise customer to a bundled Microsoft tool will often offer significant discounts (20 to 40%) to retain the business.
Leverage in EA renewal negotiations. The aggregate redundancy cost figure is a powerful data point in your EA renewal. Present it as a total ecosystem cost: “Our combined Microsoft E5 plus third-party overlap spend is $10.4M. We need to bring that below $8M. Either Microsoft helps us get there through better E5 pricing, or we downgrade portions of our EA and retain the third-party tools at their discounted renewal rates.” This framing forces Microsoft to compete not just on E5 pricing but on the total cost of your software portfolio.
“The most powerful negotiation position is when you have genuine alternatives. Your redundancy analysis creates exactly that leverage, because you can credibly walk toward either Microsoft or the third-party vendor depending on who offers the better commercial outcome.”
Fredrik Filipsson, Co-Founder, Redress CompliancePre-purchase overlap check. Establish a mandatory review process: before any new software purchase or SaaS subscription is approved, the requesting team must document whether equivalent functionality exists in the current Microsoft 365 suite. If it does, the purchase requires explicit justification explaining why the Microsoft capability is insufficient and a cost comparison including the “already paid for” Microsoft alternative. This single governance control prevents the most common source of new redundancy: departmental purchases made without awareness of existing enterprise capabilities.
Renewal-triggered rationalisation. Attach an overlap audit to every major software renewal event, both Microsoft EA renewals and third-party contract renewals. When a third-party contract approaches renewal, evaluate whether the Microsoft alternative has matured sufficiently to replace it. When the Microsoft EA approaches renewal, evaluate whether the current licence tier is justified by actual usage or whether overlapping third-party tools have made portions of the bundle unnecessary.
Centralised software portfolio visibility. Maintain a live catalogue of all enterprise software that maps products to functional capabilities. When any team requests a tool for “file sharing,” “threat detection,” or “business intelligence,” the catalogue immediately surfaces the existing enterprise tools that serve that function. This visibility prevents accidental redundancy from information gaps, the most common and most avoidable source of duplicate spend.
Annual software rationalisation review. Conduct a formal annual review of the complete software portfolio against current Microsoft 365 capabilities. Microsoft updates its platform continuously. Features that were insufficient 18 months ago may now be fully competitive with the third-party tool you retained. This annual review ensures that rationalisation decisions are revisited as both Microsoft’s capabilities and your organisation’s needs evolve.
Free self-service tools to assess your Microsoft licensing position, identify optimisation opportunities, and benchmark your EA discount levels against market data.
Microsoft Assessment Tools →| Step | Action | Key Activities |
|---|---|---|
| 1 | Complete Software Inventory | Catalogue every product across 8 overlap categories. Document annual cost, active user count, actual usage metrics, contract renewal date, and business process dependency. Include departmental SaaS, shadow IT, and tools purchased outside central procurement. |
| 2 | Map E5 Feature Utilisation | Audit which E5 features are actually deployed and adopted. Use M365 Admin Centre usage reports, Microsoft Secure Score, and Compliance Manager. Identify features licensed but not deployed (shelfware within E5) and features deployed but underutilised. |
| 3 | Quantify Overlap Cost | Calculate total annual cost of each redundancy: third-party licence cost, internal support overhead, training duplication, and integration complexity. Produce a single “total redundancy cost” figure. Present to executive leadership as the cost of inaction. |
| 4 | Assign Decision Path | For each category, determine: consolidate onto Microsoft (retire third-party), retain third-party (downgrade Microsoft licensing), or hybrid approach (different paths for different user segments). Document rationale, expected savings, migration effort, risk, and timeline. |
| 5 | Pilot Microsoft Alternatives | Run 60 to 90 day pilot with 100 to 500 users for every category where you plan to consolidate onto Microsoft. Include the most demanding user groups, not just early adopters. Document functional gaps and determine whether they are deal-breakers or manageable limitations. |
| 6 | Align with Contract Renewal Dates | Map third-party and EA renewal dates onto a single timeline. Plan retirements to coincide with natural contract expiration. If a third-party contract renews before migration completes, negotiate a short-term renewal (6 to 12 months) rather than multi-year commitment. |
| 7 | Deploy Negotiation Leverage | Use redundancy analysis to negotiate with Microsoft (better E5 pricing or funded migration support), with third-party vendors (retention discounts based on Microsoft consolidation threat), and internally (executive approval for rationalisation investment). Run negotiations in parallel with migration. |
| 8 | Implement Governance Controls | Establish pre-purchase overlap check, renewal-triggered rationalisation audit, centralised software catalogue, and annual review process. Assign ownership to specific roles (SAM manager, IT procurement lead, CTO office). Without governance, redundancy re-emerges within 12 to 18 months. |
Start with the highest-value overlaps (typically telephony and endpoint security) where the annual savings are largest and the Microsoft alternative is most mature. Quick wins in storage and conferencing can be executed in parallel with minimal disruption. Save the more nuanced decisions (BI, identity, information protection) for the second wave, after the first consolidation projects establish organisational confidence in the process.
Enterprises typically save 15 to 25% of their combined Microsoft-plus-third-party software spend through systematic redundancy elimination. For a 5,000-user organisation spending $6M on M365 E5 and $2M on overlapping third-party tools, total savings of $800,000 to $1,500,000 annually are realistic. The savings come from three sources: direct elimination of redundant third-party licences, Microsoft licence downgrades where E5 features are not used, and improved negotiation leverage with both Microsoft and third-party vendors based on your redundancy analysis.
Microsoft Defender for Endpoint has matured significantly and now ranks alongside dedicated EDR vendors in independent evaluations (MITRE ATT&CK, Gartner). For many enterprises, Defender provides sufficient endpoint protection, particularly when combined with the broader Microsoft security stack (Defender for Identity, Defender for Cloud Apps, Sentinel SIEM). However, organisations with mature security operations centres that have built custom workflows, threat hunting processes, and integrations around CrowdStrike or SentinelOne may find switching costly and disruptive. The decision should be based on your security team’s assessment of specific detection gaps, not on vendor marketing claims from either side.
Yes, and this is one of the most effective cost-reduction strategies available. E3 provides core productivity (Office apps, Exchange, SharePoint, Teams, OneDrive) at approximately 40% lower cost than E5. The features excluded from E3 include advanced security (Defender for Endpoint P2, Defender for Office 365 P2), advanced compliance (Purview Premium, eDiscovery Premium), Power BI Pro, Teams Phone System, and Entra ID P2. If these features are provided by third-party tools or are not needed by specific user populations, those users can be moved to E3 without functional loss. A typical segmentation moves 40 to 60% of users from E5 to E3, saving $15 to $22 per user per month.
Treat it as a structured migration project with four phases. First, pilot the Microsoft capability with a small user group (100 to 500 users) for 60 to 90 days to validate functionality and identify gaps. Second, develop a migration plan covering data migration (files from Box to OneDrive, policies from Proofpoint to Defender), integration changes (APIs, SIEM connections, workflow automation), and user training. Third, execute the migration in waves, starting with least-critical user groups and progressing to mission-critical populations. Fourth, run the old and new tools in parallel for 30 to 60 days before fully decommissioning the legacy tool. Align the retirement with the third-party contract expiration to avoid early termination penalties.
Resistance is common and should be addressed through data rather than mandate. Present the cost of maintaining the redundant tool (both direct licence cost and indirect overhead), demonstrate that the Microsoft alternative meets the functional requirements through a pilot, and establish a clear escalation path for teams that believe the Microsoft tool is genuinely insufficient. If a department can articulate specific capability gaps that justify the additional cost, accommodate them, but require formal justification with a documented business case. In our experience, 70 to 80% of resistance dissolves when teams actually test the Microsoft alternative, and the remaining 20 to 30% often identifies legitimate capability gaps that inform a hybrid approach.
Complete single-vendor consolidation maximises cost efficiency and operational simplicity but introduces concentration risk. If Microsoft experiences a major outage, every affected capability goes down simultaneously. Most enterprises are best served by a thoughtful hybrid: consolidate onto Microsoft where the capability is strong and the cost saving is clear (storage, conferencing, basic BI, email security), retain specialist third-party tools where they provide genuinely superior capability (advanced EDR, complex analytics, specialised identity federation), and maintain at least one critical function on a non-Microsoft platform as an operational resilience measure. The goal is not zero third-party tools. It is zero redundant tools where you are paying twice for the same outcome.
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