Microsoft 365 licensing is one of the largest line items in most IT budgets. It is also one of the least scrutinised.
June 2026 | 6 min read
At a Glance
1. Why Microsoft 365 Over-Licensing Costs Are Harder to Control Than They Look
Microsoft 365 licensing feels straightforward until you are the one managing a multi-thousand-seat tenant through mergers, team restructuring, and rolling product changes. The E3-versus-E5 decision made two years ago no longer reflects how the business uses Microsoft. Copilot licences were added in a pilot that ran longer than planned. Guest access is uncounted. Shared mailboxes are licensed. And nobody is quite sure who approved the third-party app subscriptions that now appear on four separate invoices.
The result is a Microsoft 365 licensing estate that is almost certainly overspent, with the excess distributed across enough budget lines that no single owner has the full picture. For IT directors and CFOs trying to find sustainable cost reductions without compromising capability, this is the problem worth solving.
“The average Microsoft 365 tenant is paying for 30 to 50 per cent more capability than it is actively using.”
2. The Most Common Sources of Microsoft 365 over-licensing
Microsoft 365 over-licensing is rarely caused by a single decision. It accumulates through a pattern of small, reasonable choices made without visibility of the whole.
Inactive and unassigned licences. Leavers whose accounts were disabled but not deprovisioned. Project-based hires whose licences were not reclaimed after contract end. Licences assigned during a rollout that were never actually used.
Over-licensed tiers. Users on E5 who only need E3 capability. Teams with Copilot licences that were never activated. E5 compliance and security add-ons assigned as a block rather than to the users who need them.
Duplicate functionality. Third-party tools for archiving, backup, or security that overlap with native Microsoft capabilities already included in the licence. Paying twice for the same outcome is more common than most organisations realise.
Storage overspend. SharePoint storage purchased in addition to the tenant allocation because no one has addressed ROT data, large file accumulation, or the absence of a storage optimisation policy.
Guest and external users. Guests added to Teams and SharePoint sites who retain access long after the project ends. Depending on the licence model, these can count against the tenant allocation or create audit exposure.
3. What Right-Sizing Actually Means for an Enterprise Tenant
Right-sizing is not a one-off downgrade exercise. It is a continuous process of matching licence assignment to actual usage, with visibility built in so the gap does not reopen over time.
Practically, it involves three activities. First, usage baselining: understanding which licences are actively used, which are dormant, and which are assigned to accounts that serve no active user. Second, tier alignment: comparing actual feature usage against what each licence tier includes, and identifying where users are consistently using only a subset of what they are paying for. Third, renewal preparation: using the data to negotiate with Microsoft from a position of knowledge rather than assumption.
The challenge with all three is data. Microsoft 365 admin centre usage reports provide some visibility, but they are workload-specific, not user-level across the whole estate, and they do not surface the cross-licence patterns that reveal the largest savings opportunities. This is where purpose-built governance tooling changes the outcome.
4. The CFO View: Connecting M365 Licence Spend to Business Outcomes
Finance leaders rarely have visibility into Microsoft 365 licence spend at a granular level. What arrives on the invoice is a monthly total. What sits behind it, which users, which tiers, which underutilised add-ons, is held in the IT team’s spreadsheets, if it is tracked at all.
This creates a structural problem at renewal time. Without a clear view of utilisation, organisations tend to renew at current or increased volumes, accepting Microsoft’s default pricing rather than negotiating from evidence. The 30% average licence Microsoft 365 cost reduction that TeamsFox customers achieve is not a discount. It is the result of removing spend that was already invisible.
For a CFO building a case for Microsoft 365 cost reduction, the most useful framing is not “what can we cut” but “what are we paying for that nobody is using.” That question has a concrete answer, but only once the usage data exists to support it.
“A 5,000-user tenant that right-sizes its Microsoft 365 licensing and storage can recover more than €700,000 over five years, without reducing capability for active users.”
5. How to Build a Microsoft 365 Licence Optimisation Programme That Sticks
One-off licence audits produce one-off savings. The drift begins again immediately. A Microsoft 365 licence optimisation programme that delivers sustained returns requires four things.
Continuous monitoring. Licence assignment and usage data updated in near-real time, not pulled quarterly for a manual review. New assignments, departures, and tier changes reflected automatically.
Automated reclaim triggers. When a user account is disabled, the licence reclaim should be automatic or near-automatic, not dependent on a manual ticket. The same applies to licences that have been inactive beyond a defined threshold.
Cross-workload visibility. Microsoft 365 Licence optimisation is inseparable from storage, governance, and security posture. An E5 licence assigned because of perceived compliance need may be unnecessary once Purview policies are correctly configured. Visibility across workloads surfaces these overlaps.
Renewal readiness reporting. A structured view of utilisation by tier, by team, and by feature set, available at least 90 days before the Microsoft renewal date, so negotiation is based on evidence rather than habit.
6. Microsoft 365 Cost Reduction: How TeamsFox Continuously Optimises License Costs
TeamsFox gives IT and finance a shared, real-time view of Microsoft 365 licence utilisation across the entire tenant. Inactive accounts are flagged automatically. Underutilised tier assignments are surfaced with recommendations. Storage waste is quantified alongside M365 licence waste, so the full cost picture is visible in one place.
Organisations using TeamsFox report an average 30% Microsoft 365 cost reduction through license optimisation, with no reduction in capability for active users. The savings come from visibility: knowing what is assigned, what is used, and what can be safely reclaimed or right-sized.
For organisations approaching a Microsoft 365 renewal, a free tenant analysis from TeamsFox provides the usage baseline needed to negotiate from a position of knowledge rather than assumption.
About TeamsFox
TeamsFox is the Microsoft 365 governance and optimisation platform that gives IT and finance teams real-time visibility into licence usage, storage waste, and access risk across the entire tenant. Headquartered in Düsseldorf and trusted in 20+ countries, TeamsFox helps organisations reduce Microsoft 365 over-licensing spend by an average of 30%, cut storage costs by 40%, and free up 60% of IT administrative time.