October 13, 2026 Is a Double Deadline: Office LTSC 2021 End of Support Meets Windows 10 ESU Year 2 — A Three-Week Triage Plan

Why one date, two deadlines

Microsoft's lifecycle database lists Office LTSC 2021's end of support as October 13, 2026 (Pacific time), and Message Center post MC1472429 (published September 15, 2026) confirms the same date for Office LTSC 2021, Visio LTSC 2021 and Project LTSC 2021. After that date those products receive no security fixes, no bug fixes, and no support.

Windows 10 reached end of support on October 14, 2025. Organizations bought a year of Extended Security Updates at Microsoft's published $61 per device; that first ESU year covers through October 13, 2026. Microsoft prices Year 2 at $122 per device and Year 3 at $244, and the program is cumulative: if you skipped Year 1 you pay for it retroactively before Year 2 activates. Windows 10 VMs on Windows 365, Azure Virtual Desktop, Azure VMs and the other Azure-hosted options listed by Microsoft receive ESU at no additional cost. Devices must be on Windows 10 version 22H2 to enroll.

The two programs are administered separately, so most organizations have two owners, two spreadsheets and two budgets. The exposure sits where the spreadsheets overlap: a Windows 10 PC with Office LTSC 2021 installed. From October 14, that device runs an unsupported operating system (unless ESU Year 2 is bought) and an unsupported Office suite, and no amount of endpoint protection converts that into a defensible position for an auditor, a cyber-insurer, or a CMMC or HIPAA assessor.

What Microsoft recommends, and what it quietly signals

MC1472429 and the September Partner Center guidance lay out the same paths:

• Enterprises: Microsoft 365 E3 as the primary path, with Office 365 E3 or Microsoft 365 Apps for enterprise as the fallback where you only need the applications.
• Organizations under 300 users: Microsoft 365 Business Premium, Business Standard, or Microsoft 365 Apps for business.
• Project and Visio: Project Plan 3 and Visio Plan 2, the cloud replacements.
• Disconnected or regulated environments: Office LTSC 2024, Project LTSC 2024 and Visio LTSC 2024, supported through October 2029.

Two details in the partner guidance matter more than they look. First, Microsoft 365 Copilot is supported only on cloud-backed apps — a perpetual Office SKU is a hard ceiling on Copilot regardless of what license you buy later. Second, the Azure Information Protection labeling client for perpetual Office has been retired, so organizations that rely on sensitivity labels in Office LTSC lose the labeling client path as well. Read together, Microsoft is telling you that LTSC 2024 is a legitimate destination for air-gapped and regulated estates and a poor destination for everyone else.

The four device paths

Every device in the overlap set lands in exactly one of these. Resist the urge to pick one path for the fleet; the economics are per device.

Path A — Migrate the device to Windows 11 and Microsoft 365 Apps. For hardware that meets Windows 11 requirements, this is the free-upgrade path for the OS and a subscription path for Office. It removes both deadlines permanently and makes the device Copilot-eligible.

Path B — Replace the hardware. For Windows 11-ineligible PCs (TPM 2.0, supported CPU) that must stay physical, the ESU arithmetic often favors replacement: two more years of ESU is $366 per device at Microsoft's published prices ($122 + $244) before you count the Office subscription you still have to buy. A refreshed device with Microsoft 365 Apps ends the conversation.

Path C — Move the workload to the cloud PC. Windows 365 and Azure Virtual Desktop include Windows 10 ESU at no extra cost, and the Office question resolves itself because Microsoft 365 Apps is the natural suite on a cloud PC. This is the fastest path for contractors, kiosks, shared-shift devices and legacy line-of-business apps that pin the OS.

Path D — Renew ESU Year 2 and go to LTSC 2024, deliberately. For lab instruments, manufacturing floor systems, disconnected government enclaves and anything with a documented exit date beyond 2027, buy ESU Year 2 and deploy Office LTSC 2024. Write the exit date down. ESU Year 3 at Microsoft's $244 exists to make you leave.

The three-week triage plan

You have three weeks from the publication of this article. It is enough if the sequence is right.

Week 1 — Count.

1. Pull the device inventory from Intune or Configuration Manager: OS build, Windows 11 eligibility (the Endpoint analytics Work from anywhere report gives hardware readiness), Office build and channel, last sign-in, primary user.
2. Filter to the overlap: Windows 10 and an Office 2021 perpetual build (Office LTSC 2021 reports build 16.0.14332.x lineage; use the Office apps inventory in Intune or the Office Deployment Tool inventory if you do not have Intune).
3. Tag every overlap device A/B/C/D using the rules above. If a device has no primary user and no sign-in in 90 days, it is a retirement candidate, not a licensing decision.
4. Separate Project and Visio users; they are a smaller population with their own SKUs (Plan 3 and Plan 2).

Week 2 — Price and decide.

5. Run the licensing arithmetic for Path A users. The choices are Microsoft 365 Apps for enterprise (applications only), Microsoft 365 E3 (applications plus Windows Enterprise, Intune, Entra ID P1), or — if the same population is on your Copilot shortlist — Microsoft 365 E7 at Microsoft's list price of $99 per user per month, which bundles E5, Copilot, Agent 365 and the Entra Suite. Do not buy E7 to solve an Office deadline; buy it only if the Copilot and agent decision is already made.
6. Get written ESU Year 2 quotes for the Path D count only. The cumulative rule means any device that skipped Year 1 costs $183 at Microsoft's published prices ($61 + $122) to bring current.
7. For Path C, size the cloud-PC pool by concurrency, not headcount.
8. Decide the Path B refresh budget using the $366 two-year ESU cost as the comparison, and add the Office subscription you would buy anyway.

Week 3 — Deploy the first wave and stop the bleeding.

9. Deploy Microsoft 365 Apps to the Path A population using the Office Deployment Tool or the Intune Microsoft 365 Apps policy, with Monthly Enterprise Channel as the default and Semi-Annual only where a documented application dependency requires it. Remove LTSC 2021 as part of the same deployment.
10. Enroll Path D devices in ESU Year 2 before October 13 so there is no coverage gap, and stage Office LTSC 2024 through the same deployment tooling.
11. Move Path C users to their cloud PC and reassign the physical device to Path B or retirement.
12. Re-run the inventory on October 14 and publish the residual count to whoever owns risk. A residual of zero is rare in week three; a residual with names, owners and dates is a defensible position.

The mistakes we keep seeing

• Buying ESU for the fleet “to be safe.” ESU is per device, doubles each year, and is cumulative. Blanket purchases turn a triage problem into a recurring line item.
• Treating Office LTSC 2024 as the default upgrade. It is the right answer for disconnected estates and the wrong answer for anyone who expects Copilot, sensitivity labeling through the modern client, or continuous feature updates.
• Migrating Office and leaving Windows 10. From October 14 you will have a supported Office on an unsupported OS; that is still a finding.
• Letting the CSP order settle it. Your reseller can sell ESU Year 2 and E3 in one order; only your inventory can say how many of each.
• Forgetting Project and Visio. They share the deadline and are often installed on the finance and PMO machines that matter most.

Frequently asked questions