If your business bought Office 2021 as a one-off purchase, Microsoft stopped supporting it on 13 October 2026. Nothing changed on your screen that morning. Word, Excel and Outlook all still open. But from now on they're running without security fixes, and with no safety net if something breaks.
Office 2021 end of support: the quick answer
- —Your apps still work. Office 2021 keeps opening and saving files as normal.
- —No more security fixes or help. Microsoft no longer fixes bugs or security holes, and there's no paid extension like there was for Windows 10.
- —No longer supported with Microsoft 365. Office 2021 was only supported for connecting to Microsoft 365 email, OneDrive and SharePoint until 13 October 2026.
- —What to do: for most small businesses, move everyone onto Microsoft 365 desktop apps. If you can't, Office 2024 is supported until October 2029.
What exactly ended on 13 October
This affects every edition of Office 2021, on Windows and Mac: Office Home & Student 2021, Office Home & Business 2021, Office Professional 2021 and Office LTSC 2021, plus Visio 2021 and Project 2021. According to Microsoft:
- —There are no more security updates, bug fixes or software updates.
- —Phone and chat support has ended, and the online help is no longer being updated.
- —There is no extension and no Extended Security Updates programme.
The part most people miss is the connection to Microsoft 365. Microsoft keeps a list of which Office versions are supported for connecting to Exchange Online (your email), SharePoint and OneDrive. Office 2021 came off that list on 13 October. Microsoft says older versions may still connect, but they "might not be able to use all the latest functionality" and "might encounter other unexpected performance or reliability issues", because Microsoft no longer tests its changes against them.
In plain terms: Outlook 2021 will probably keep working with your Microsoft 365 email for a while. But when something does go wrong, such as Outlook freezing, a shared mailbox not loading or files not syncing, the fix is going to be "upgrade".
Why it matters more for a business than at home
- —Attachments are the main way attackers get in. A booby-trapped Word or Excel file is aimed at exactly the gaps that no longer get patched.
- —Clients, insurers and regulators ask. Law firms, accountants and financial advisers are often asked to confirm they run supported software. Cyber insurance and certifications such as Cyber Essentials in the UK expect it too.
- —Mixed versions cause daily friction. When half the team is on Office 2021 and half on Microsoft 365, co-authoring, Outlook features and shared templates stop behaving the same for everyone.
Step 1: Check which version everyone has
Many small businesses have a mix and don't realise it: a few laptops bought with Office 2021, and newer starters on Microsoft 365. Check each computer:
- —Windows: open Word, go to File → Account and look under Product Information. "Office Home & Business 2021" or "Office LTSC Professional Plus 2021" means you're affected. "Microsoft 365 Apps for business" or "Microsoft 365 Apps for enterprise" means you're fine.
- —Mac: open Word and choose Word → About Word. A "2021" in the name means you're affected.
- —Keep a simple list of each person, their computer and their Office version. You'll need it to choose licences.
Step 2: Choose your option
- —Option A: Microsoft 365 desktop apps (best for most businesses). If you already pay for Microsoft 365 email on Business Basic, it only includes the web and mobile apps. Moving those people to Business Standard adds the full desktop Word, Excel, PowerPoint and Outlook, always updated and always supported. It's a licence change in the admin centre, so nobody's email or files move. If you handle sensitive client data, Business Premium adds device and security controls on top.
- —Option B: Office 2024 (one-off purchase). Office Home & Business 2024 is supported until October 2029 and suits a computer that rarely connects to the internet or a business that can't take on another subscription. The catch is that it gets no new features, and you'll be making this same decision again in three years.
- —Option C: the free web apps only. Word, Excel and PowerPoint in the browser are enough for some roles, such as people who mostly read and lightly edit. It rarely works for anyone who lives in Excel or Outlook all day.
- —Option D: do nothing. It's fine for a home computer used for the odd letter. It isn't a sensible choice for a business that emails client documents.
Step 3: Switch without breaking anything
The upgrade itself is simple, but a few things catch people out:
- —Rescue your Publisher files first. Office 2021 was the last version where Publisher still opens. Neither Office 2024 nor Microsoft 365 includes it, so convert your .pub files before you uninstall anything.
- —Uninstall Office 2021 before installing the new apps. Two versions side by side cause errors and confusing duplicate icons. Use Settings → Apps on Windows.
- —Install from your Microsoft 365 account. Sign in at microsoft365.com, choose Install apps, then sign in to Word and Outlook with your work account.
- —Check Outlook properly. Make sure shared mailboxes, calendars and email signatures all came across. Signatures are the thing people notice missing first.
- —Do one person first. Upgrade one computer, use it for a day, then do the rest of the team.
Your quick checklist
- —Check the Office version on every computer and write it down.
- —Decide between Microsoft 365 desktop apps and Office 2024 for each person.
- —Convert any Publisher files before removing Office 2021.
- —Uninstall Office 2021, then install the new apps from microsoft365.com.
- —Check Outlook, shared mailboxes, signatures and OneDrive sync on each computer.
Use it as a chance to tidy up
Moving everyone onto the same Microsoft 365 apps is a good moment to sort out where files live too. If your team still saves to desktops and old shared drives, read OneDrive vs SharePoint vs Teams, or work through my free Microsoft 365 setup checklist.
If you'd rather have it done for you, I help small law firms, accounting firms and other growing businesses move onto Microsoft 365 properly through my Microsoft 365 setup service.
