Microsoft licensing cost optimization starts with one comparison: the number of paid Microsoft 365 seats against the number of people who use them. Seats outlive the employees, projects, and mailboxes they were bought for, and each one renews at full price. Under the New Commerce Experience (NCE), you can only reduce an annual subscription in the first seven days of its term. Any seat you retain at renewal stays on the bill for another year.
The three patterns below are where a license overpayment analysis usually finds savings first. You can check each one from the Microsoft 365 admin center or the Microsoft Entra admin center without third-party tools.
Offboarding workflows often block sign-in for a departing employee and stop there. Blocking sign-in leaves the license assigned, so you keep paying for that seat.
Microsoft’s guidance on detecting inactive user accounts in Entra ID recommends adding the last interactive sign-in time to the Users view and filtering by date. Microsoft treats 90 to 180 days without a sign-in as a reasonable inactivity window for many organizations. To pull the same data at scale through Microsoft Graph, you need Microsoft Entra ID P1 or P2 for the lastSuccessfulSignInDateTime property.
Start with these accounts.
Stale accounts also add security exposure, since each licensed identity no one monitors is a credential an attacker can target. Cleaning them up improves Microsoft licensing compliance and your security posture in the same pass. Before reclaiming anything, confirm the account is not tied to a leave of absence, a seasonal role, or a mailbox your retention policy requires you to keep.
Overpayment also hides in users who are licensed for far more than they use. The Microsoft 365 apps Active users report shows each user’s last active date in Exchange, OneDrive, SharePoint, Teams, and Viva Engage, along with license assignment dates, across 7, 30, 90, or 180 days. Export it to CSV and compare activity against the SKU each person holds.
Common mismatches include the following:
Timing affects how much you can recover. NCE allows upgrades during a term, while downgrades generally wait for renewal, so put right-sizing decisions on the calendar well before your renewal date.
A common offboarding step converts a leaver’s mailbox to a shared mailbox so the team keeps access, and the license frequently stays attached. Microsoft requires a license on a shared mailbox only when it stores more than 50 GB, uses in-place archiving, or is placed on a litigation hold. Microsoft’s instructions to remove a license from a shared mailbox also point out that unassigning a license does not stop the charge until you reduce the subscription itself.
The same rule applies to every user license you reclaim, so compare purchased seats with assigned seats for each product under Billing, then Licenses. Unassigned seats bought for hiring plans that never materialized cost the same as seats in use.
Run the check in reverse as well. A shared mailbox that exceeds 50 GB, has an archive, or is on hold without the right license is a compliance problem, so a software licensing audit should flag under-licensing alongside waste.
New hires, departures, and project changes create idle seats every quarter. Treat the cleanup as a recurring process and run these steps at least 90 days before each renewal.
Price changes raise the cost of every idle seat. The 5% CSP uplift covered in our October 2026 Microsoft licensing update is one example. Organizations moving off an Enterprise Agreement should also weigh whether MCA-E or CSP replaces their EA before they commit to new seat counts. Build the review into your broader IT cost optimization cycle so finance sees licensing numbers that match headcount.
Identifying idle seats is the starting point. The harder decisions are which seats to cut or downgrade and how to restructure your agreement without creating compliance exposure. Those decisions require licensing expertise and a working knowledge of your contract terms.
CloudServus is a Top 1% Microsoft Solutions Partner globally and an Azure Expert MSP. Fewer than 1% of Microsoft partners hold that designation, because earning it requires an independent audit of technical capability and customer delivery. The CloudServus Microsoft Licensing Assessment covers usage audits, license deduplication, group-based licensing, and NCE program fit. The licensing optimization review begins with your current licensing statement. From there, our licensing team works with your IT and finance leaders to turn the findings into a renewal plan your organization can defend.