October 2026 Microsoft Deadlines: Office LTSC 2021, Windows 10 ESU and Server 2012 Support — Megathread

Patch Tuesday is six days away, and this one carries more weight than usual. On October 13, three separate Microsoft support deadlines land on the same day: Office 2021 reaches end of support, the first year of Windows 10 Extended Security Updates expires, and the third and final ESU year for Windows Server 2012 and 2012 R2 comes to a close. If you manage PCs or servers for a living, or you are just someone who bought Office outright and never looked back, this is the week to pay attention.

What ends on October 13​

Let us get the inventory straight, because the list is longer than most people realize.
First, Office 2021 in all its forms: Office Home & Student 2021, Home & Business 2021, Professional 2021, and Office LTSC 2021, along with Project LTSC 2021 and Visio LTSC 2021. After October 13, Microsoft stops delivering security updates, bug fixes, and technical support for all of them. The applications will keep opening. Your documents will still be there. But every vulnerability discovered from that day forward stays open forever, at least as far as Microsoft is concerned.
Second, Windows 10 ESU Year 1. Devices enrolled in the Extended Security Updates program need Year 2 to keep receiving patches. The commercial price was $61 per device for Year 1, and it doubles to $122 for Year 2, which runs through October 12, 2027. ESU requires Windows 10 version 22H2, and enrollment is cumulative, which matters more than most people think. More on that below.
Third, Windows Server 2012 and 2012 R2. The three-year ESU period ends on October 13, and the security update shipped that day is the last one. Microsoft lists no fourth year. After a decade-plus of service, these servers are on their own.
The supporting cast is worth noting too. Windows 11 version 24H2 Home and Pro editions reach end of servicing the same day, so those machines need to move to 25H2. Windows Server 2022 shifts from mainstream to extended support. And Publisher, the long-neglected desktop publishing app, reaches end of support in October as well.

Office 2021: the hard stop​

Of the three deadlines, the Office one is the sharpest, and it is the one most likely to catch people off guard. Here is why: there is no ESU program for Office 2021. There is no extended support phase at all.
That is a genuine break with history. Perpetual Office licenses used to get ten years: five of mainstream support, five of extended. Starting with Office 2021, Microsoft eliminated the extended phase entirely, cutting the supported lifespan in half. Office LTSC 2021 follows the Fixed Lifecycle Policy: five years of mainstream support, then nothing. October 13 is not a bend in the road. It is a wall.
Microsoft's official recommendation is to move to Microsoft 365 or to Office 2024 and Office LTSC 2024, which are supported until October 9, 2029. For organizations that deliberately avoided subscriptions, perhaps for regulatory, budget, or philosophical reasons, LTSC 2024 is the natural landing zone, but it means buying new licenses and testing macros, add-ins, and templates before the move. That work takes weeks, not days.
There are alternatives for the stubborn. LibreOffice and OnlyOffice have matured considerably and keep everything on premises. And 0patch, the micropatching firm, has announced it will "security-adopt" Office 2021 once Microsoft walks away, offering critical security micropatches for at least three more years on a paid basis. That is a legitimate bridge for machines that cannot migrate yet, but be clear-eyed about what it is: third-party patches on an unsupported product. Your auditor will still write it up.
One more thing people get wrong: unsupported does not mean it stops working. On October 14, Word will open exactly as it did on October 12. What changes is invisible until it is not: the next critical vulnerability in the Office suite simply never gets fixed on your machine. The risk compounds monthly.

Windows 10 ESU Year 2: the price doubles​

Windows 10 is the zombie that will not die. StatCounter's September 2026 data still shows it running on roughly 28 percent of Windows desktops and laptops. A year ago, when free support ended, a large share of those machines bought breathing room through ESU. That breathing room now needs renewing, at double the price.
The commercial math: Year 1 was $61 per device. Year 2 is $122 per device, running October 14, 2026 through October 12, 2027. Year 3 will be $244. And because ESU is cumulative, there is no discount for sitting out a year. A business that skipped Year 1 and enrolls now pays $183 per device ($61 plus $122) for one year of coverage, having spent the previous twelve months unpatched. Waiting saved nothing.
ESU is also narrower than people assume. It delivers security updates rated critical and important. No new features, no non-security fixes, no general technical support. Its job is to buy time, not to make Windows 10 a long-term platform. And it strictly requires Windows 10 version 22H2; anything older is not eligible, full stop.
Consumers are on a different track, and the distinction matters. The home-user ESU program, free with a Microsoft account settings sync, 1,000 Rewards points, or a one-time $30 purchase, was extended to October 12, 2027. But Microsoft is explicit that it cannot be used in commercial scenarios, and it is not even offered on domain-joined, Entra-joined, or MDM-enrolled devices. If it is a company PC, the consumer program does not apply.
Two things that soften the blow slightly, and one that does not: Microsoft will keep delivering Defender security intelligence updates on Windows 10 22H2 through at least October 2028, and Edge plus the WebView2 Runtime get updates until at least October 2028 without ESU. That keeps the browser and the antivirus current. It does not patch the kernel, drivers, or system services, which is where the serious vulnerabilities live. Do not let anyone tell you Defender updates mean the machine is covered.

Server 2012 and 2012 R2: the last patch​

Then there are the servers. Windows Server 2012 and 2012 R2 have been on extended life support for three years, and October 13 is the end of the line. The update that ships that day is the final security update Microsoft will ever produce for these operating systems.
The options are the ones you already know, which does not make them easier: migrate the workloads to a supported Windows Server version, move them to Azure, or decommission. What you cannot do is nothing. An unpatched server on the network is not a risk you accept quietly; it is the kind of thing that shows up in an incident report with your name on it.
If you still have 2012-era machines in production, you almost certainly know about them already, and you have probably been deferring the migration for reasons that felt good at the time. The deferral window is now closed.

The overlap problem​

Here is the scenario that should worry IT departments the most, because it is depressingly common: a Windows 10 PC running Office LTSC 2021, pulling files from a Windows Server 2012 file server. Without action, on October 14 that chain is unsupported at every single link. The endpoint, the productivity suite, and the server it depends on all stop receiving security updates on the same day.
This is where the conversation moves beyond IT and into risk. Cyber insurance underwriters routinely ask whether all systems run supported, patched software. An unsupported operating system can complicate a renewal or a claim. Compliance frameworks like HIPAA and PCI DSS expect known vulnerabilities to be patched, and "we didn't renew ESU" is a hard answer to give an auditor. Attackers do not need your newest server. They need one unpatched machine on the same network as everything else.
Start with the overlap. Find the machines where two or three of these deadlines apply at once, and move those first.

What to do this week​

Six days is not a lot of time, but it is enough to get organized. Here is the short version of the triage.
Inventory everything. For each device, record the Windows version and edition (winver will tell you) and the Office version (File, then Account). For anything beyond a handful of machines, use your device management tooling. You cannot make decisions about devices you have not counted. Flag anything not on Windows 10 22H2 now, because those machines are not ESU-eligible at any price.
Sort every device into a path. The industry shorthand that has emerged is four paths: move to Microsoft 365 Apps on a supported Windows 11 device; move to Office LTSC 2024 for machines that must stay on premises and off subscriptions; buy Windows 10 ESU Year 2 as a twelve-month bridge for the counted quantity that truly cannot move yet; or retire and replace. Servers get their own decision: migrate, move to Azure, or decommission.
Buy only what you counted. ESU Year 2 should be purchased for the specific devices that need the bridge, through volume licensing or a CSP partner, after confirming 22H2. Do not blanket-buy; at $122 a seat doubling to $244, every unnecessary license is money burned.
Test the Office move before you commit to it. Macros, COM add-ins, and document templates are where Office migrations go to die. A pilot group running LTSC 2024 or Microsoft 365 Apps for a week will surface the breakage while there is still time to fix it.
Move Windows 11 24H2 Home and Pro machines to 25H2. It is the easiest item on this list and the easiest to forget.
The consulting firm EPC Group published a three-week triage plan built around exactly this sorting exercise, and it is worth a read if you want the checklist version. The core insight is the same: decide from an inventory, not from a guess.
October 13 will come and go whether you are ready or not. The machines will keep booting. The applications will keep opening. Everything will look fine, right up until the month it does not. Six days is enough to know where you stand. Start counting.