If your business is still running Office 2021 LTSC — the one-off, perpetually licensed version rather than a Microsoft 365 subscription — it stops getting security patches on 13 October 2026. After that date, any new vulnerability found in Word, Excel, Outlook or the rest of the suite simply won’t be fixed on that install, no matter how serious it is.
What “LTSC” actually means
LTSC stands for Long-Term Servicing Channel. Microsoft sells it as a one-time purchase for businesses that specifically don’t want the regular feature updates that come with a Microsoft 365 subscription — it’s common in environments where IT wants the software to stay exactly as it is, update after update. The trade-off has always been a fixed support window, and for the 2021 release, that window closes on 13 October 2026. Microsoft’s own lifecycle page confirms this is a hard end date, not an estimate.
This is different from Office running out of “features” — the programs will keep opening and working exactly as they did the day before. What changes is that nobody is checking for new security holes in them, or fixing the ones that get found later.
Why this matters more than it sounds
Office files are one of the most common ways malware gets into a business — a dodgy macro in a Word document, a malformed Excel file, a crafted email attachment. Security patches for Office are a genuinely active area, not a formality. Once patching stops, every new flaw discovered in Word, Excel, Outlook or PowerPoint stays open indefinitely on that machine, and anyone using it inherits the risk without doing anything differently themselves.
It also quietly becomes a compliance gap. Cyber-insurance policies and many client contracts (particularly in legal, accounting, medical and real estate work, where confidentiality obligations are front and centre) often assume software is kept patched. An unsupported Office install can become the detail that’s hard to explain after the fact.
What to actually do about it
The practical options are straightforward:
1. Check what you’re running. If you’re not sure whether your business is on LTSC or on a Microsoft 365 subscription, that’s worth confirming first — the two can look identical day to day. 2. If you are on LTSC 2021, plan the move to Microsoft 365 (which is kept continuously patched) or, if there’s a specific reason LTSC is still needed, budget for the next LTSC release rather than staying on one that’s aged out. 3. Don’t wait for a problem to force the decision. Migrations are far less stressful when they’re planned than when they’re triggered by an incident.
If you’d like a straight answer on which licensing your business is actually running and what moving off it would involve, that’s exactly the kind of thing our IT consulting team can check for you in a few minutes rather than guessing.
The deadline itself won’t move. The only real variable is whether your business deals with it on its own schedule, or on Microsoft’s.