Microsoft Licence Transfer and Assignment Rules: Complete Enterprise Guide

Misapplying Microsoft's licence assignment and transfer rules is the second most common source of audit findings we see — after SQL Server virtualisation miscounting. The 90-day reassignment restriction trips up IT teams constantly in device refresh cycles, and the rules around perpetual licence transfers in M&A contexts are poorly understood even by experienced procurement professionals. After 500+ engagements managing $2.1B in Microsoft spend, this guide distils the transfer and assignment rules that matter most operationally — with the specific product variations that Microsoft's own documentation buries in footnotes.

The 90-Day Reassignment Rule: What It Actually Means

Microsoft's Product Terms state that once a licence is assigned to a device or user, the same licence cannot be reassigned to a different device or user for 90 calendar days. This rule was designed to prevent a single licence from simultaneously covering multiple users through rapid rotation — a "hot-desking" licence scheme.

Scope of the 90-Day Rule

Product Category	90-Day Rule Applies	Assignment Unit	Notes
Microsoft 365 (per-user)	✅ Yes (with exceptions)	Named user	Immediate reassignment permitted when user leaves org
Windows Server	✅ Yes	Physical server/VM per licence assignment	90 days from last assignment date
SQL Server	✅ Yes	Physical core or Server+CAL	Critical for VMware dynamic migration management
Office perpetual (per-device)	✅ Yes	Named device	90 days from device assignment; exceptions for hardware failure
M365 Apps (per-user)	✅ Yes (with exception)	Named user	5 device installs per user; immediate reassignment on departure
Visual Studio subscriptions	✅ Yes (with exception)	Named subscriber	Immediate reassignment when subscriber leaves org
Azure Reserved Instances	⚠️ Different rule	Scope (shared/single)	Exchange/return within first 4 days; no standard 90-day rule
CAL (Client Access Licence)	✅ Yes	Named user or named device	Per-device CALs follow device; per-user CALs follow user

The Two Exceptions

The 90-day restriction has exactly two documented exceptions in Microsoft's Product Terms:

Exception 1 — Hardware failure: If the device to which a licence is assigned fails permanently (hardware failure, data destruction, physical loss or theft), the licence can be immediately reassigned to a replacement device. "Permanently fails" means the original device is no longer operational — not that it is temporarily repaired or in service. Documenting this exception requires: (a) an IT incident record confirming the failure, (b) the date of failure, (c) confirmation that the original device is being decommissioned. Without this documentation, the reassignment appears identical to a policy-violating rapid reassignment in an audit context.

Exception 2 — User departure: When the user to whom a licence is assigned leaves the organisation (resignation, termination, retirement), the licence can be immediately reassigned to a new user. "Leaves the organisation" means permanent departure, not temporary leave such as medical leave or secondment. The trigger documentation is the HR offboarding event — typically the Active Directory/Entra ID account deactivation date. For M365, ensure the deactivation is logged in the Microsoft 365 Admin Centre audit logs, which serve as primary evidence in an audit.

Perpetual Licence Transfers Between Organisations

Perpetual licences acquired under volume licensing agreements can be permanently transferred to another organisation with Microsoft's written consent. This is distinctly different from the 90-day reassignment rule — which governs reassignment within a single organisation — and involves the permanent change of licence ownership.

When Perpetual Licence Transfers Are Permitted

Microsoft permits perpetual licence transfers in the following scenarios:

• Hardware disposition: When selling computer hardware that has OEM or volume licences attached to specific devices. The licence transfers with the hardware.
• Business sale or divestiture: When a business unit or subsidiary is sold, perpetual licences used exclusively by that business unit can be transferred to the acquiring entity with Microsoft approval.
• Full entity transfer: When the entire organisation (not just a division) is acquired, all licences transfer under change of control provisions — subject to agreement assignment provisions in the EA.

Scenarios Where Perpetual Licence Transfers Are NOT Permitted

• Subscription licences (M365, Azure): These are service subscriptions, not transferable property. They cannot be sold, donated, or transferred to any other organisation.
• Licence transfer to competitors: Microsoft's Product Terms explicitly prohibit transferring licences to a Microsoft competitor. This is rarely enforced but is a documented contractual restriction.
• OEM licences (without hardware): OEM-acquired Windows Server or SQL Server licences are bound to the original hardware and cannot be transferred independently of that hardware. This is the most commonly misunderstood rule in data centre licence management.
• Academic or Government licences to commercial entities: Licences acquired under academic or government pricing programmes cannot be transferred to commercial organisations.

Licence Assignment Documentation Requirements

Proper licence assignment documentation is your audit defence. Microsoft's verification process during an audit asks two questions: what did you purchase, and where is it deployed? The assignment documentation connects the answer to question one (entitlement records in VLSC) to the answer to question two (deployment records in your SAM tool).

Minimum Documentation Standards

Product Type	Assignment Record Required	Where Maintained	Retention Period
M365 per-user	User → licence tier mapping with assignment date	Microsoft Admin Centre (authoritative) + SAM tool	Duration of licence + 5 years
Windows Server	Licence → physical host mapping with VM inventory	SAM tool + virtualisation platform records	Duration + 5 years
SQL Server	Core count per physical host (or per-VM for SE+) with virtualisation topology	SAM tool with topology engine	Duration + 5 years
CAL (per-device)	CAL → device assignment list	SAM tool / Active Directory records	Duration + 5 years
CAL (per-user)	CAL → user assignment list	SAM tool / Active Directory records	Duration + 5 years
90-day exception (hardware)	IT incident record + decommission confirmation	ITSM system + SAM tool reassignment log	5 years from reassignment date
90-day exception (user departure)	HR offboarding date + Entra ID deactivation timestamp	HR system + Microsoft Admin Centre audit log	5 years from reassignment date

Assignment Rules in Specific Scenarios

Shared Workstations and Kiosk Deployments

Shared workstations — devices used by multiple users in shift-based environments (retail, manufacturing, healthcare) — present specific assignment challenges. A single device used by 3 shift workers cannot be licenced with one per-user M365 licence; it requires either a per-device M365 F3 licence (for frontline scenarios) or individual per-user licences for each worker who uses the device.

The per-device model for M365 F1/F3 is the correct approach for shared device environments. Per-device licensing assigns the licence to the device, not the users — any authorised user can access the device without additional licence requirements. For the full frontline licensing framework, see the frontline worker licensing guide.

Contractor and Temporary Worker Assignments

Contractors using an organisation's Microsoft-licenced devices or services must be licenced under the same rules as employees. A contractor using a corporate laptop with Microsoft 365 E3 requires an M365 E3 licence — there is no "contractor exemption." However, contractors accessing corporate systems remotely (using their own devices) may qualify for External Connector licences for server products rather than full per-user/device licences, depending on the product and access scenario. For CAL rights, see the product use rights interpretation guide.

Azure Hybrid Benefit Assignment

Azure Hybrid Benefit is a use right assigned to Azure VMs, not a traditional per-device or per-user licence. AHUB must be actively applied to each eligible Azure VM in the Azure portal. The assignment rules: each Windows Server Standard licence with SA covers 2 Azure VMs up to the same or lesser edition. Each Windows Server Datacenter licence with SA covers an unlimited number of Azure VMs of any edition. The 90-day reassignment rule does not apply to AHUB reassignment between Azure VMs — AHUB can be toggled on and off any VM at any time without restriction.

For the complete AHUB optimisation guide, see the Azure Hybrid Benefit guide, and for how AHUB interacts with licence mobility provisions, see the licence mobility documentation guide.

Licence Transfer in M&A and Divestiture Contexts

The transfer rules described above for standard scenarios become significantly more complex in M&A contexts, where legal entity changes trigger specific provisions. For the complete M&A post-close operations framework — including how licence transfers interact with EA change of control provisions and TSA arrangements — see the dedicated M&A post-close licensing guide.

Practical Compliance Management for Assignment Rules

Staying compliant with Microsoft's assignment rules operationally requires building assignment tracking into your SAM programme rather than managing it as a one-off audit exercise. The SAM programme should:

• Maintain a rolling 90-day reassignment log showing every licence assignment change and the trigger (routine, exception type 1, exception type 2)
• Flag any reassignment that does not have a documented exception trigger and is within 90 days of the previous assignment
• Integrate with HR systems to automatically log user departure events that trigger Exception 2
• Integrate with ITSM to automatically log hardware failure events that trigger Exception 1
• Generate a quarterly assignment compliance report showing all assignments, exceptions used, and documentation references

For the full SAM programme framework that incorporates assignment tracking, see the SAM programme implementation guide. For the tool platforms that automate assignment tracking, see the SAM tool comparison guide.

Frequently Asked Questions

What is the 90-day reassignment restriction in Microsoft licensing?

Once a licence is assigned to a specific device or user, it cannot be reassigned to a different device or user for 90 days. Two exceptions exist: (1) the original assigned device fails permanently, and (2) the originally assigned user leaves the organisation. Outside these exceptions, reassigning within the 90-day window creates a compliance gap.

Can Microsoft EA licences be permanently transferred to another organisation?

EA subscription licences (M365, Azure) cannot be permanently transferred. Perpetual licences acquired under an EA can be permanently transferred to a third party with Microsoft's written consent, typically in M&A scenarios. The process requires a formal transfer request, takes 30–60 days, and incurs a documentation fee.

Can I reassign an M365 licence from a terminated employee to a new hire immediately?

Yes — this is explicitly covered by the second exception to the 90-day reassignment rule. When the originally assigned user leaves the organisation permanently, the licence can be immediately reassigned. The trigger documentation is the HR offboarding event and the Azure AD/Entra ID account deactivation timestamp.

Can I transfer Microsoft licences to a cloud provider for hosted deployments?

Server licences with active Software Assurance can be deployed at authorised third-party hosters through licence mobility provisions — not technically a transfer but a permitted deployment on shared infrastructure. The 90-day reassignment rule applies to reassigning the licence between servers at the hoster.

What happens to Microsoft licences in a company bankruptcy?

Subscription licences terminate if payments cease. Perpetual licences survive bankruptcy as property of the insolvent estate but cannot be transferred without Microsoft's written consent. Acquirers of bankrupt Microsoft EA customers typically need to purchase new licences.

Are there products exempt from the 90-day reassignment restriction?

Most on-premises and cloud licences are subject to the 90-day rule. Azure Reserved Instances follow different rules (exchange/return within first 4 days). Visual Studio subscriptions can be immediately reassigned when the subscriber leaves the organisation. Always verify current Product Terms for the specific product.