Author: Dan Briggs  |  Published: 27 August 2026  |  Reading time: 16 minutes

Two Microsoft deadlines land within a fortnight of each other this October, and between them they will quietly break something in a lot of Australian offices. On 1 October 2026, Microsoft 365 subscribers lose the ability to open or edit Publisher files. On 13 October 2026, Office 2021 and Office LTSC 2021 stop receiving security updates permanently.

Neither change involves a bill arriving, which is exactly why both get missed. Nothing stops working on the morning of 14 October. Word still opens. Excel still calculates. The damage is slower than that: an office productivity suite that will never be patched again, sitting on machines that open email attachments all day, in a business that may have told its insurer and its clients that it runs supported software.

Executive summary. Microsoft ends support for Office 2021 and Office LTSC 2021 on 13 October 2026, with no extension and no extended security updates. From 1 October 2026, Microsoft 365 subscribers can no longer open or edit .pub files in Publisher, and Microsoft recommends converting those files to another format first. Running an unsupported office suite after 13 October puts an Australian business outside Maturity Level One of the ASD Essential Eight, which requires that office productivity suites no longer supported by vendors are removed. For a ten-person business, the realistic options run from about $3,790 one-off for perpetual Office 2024 licences to roughly $11,844 over three years for Microsoft 365 Business Premium. The work itself is small. The problem is finding the machines, because perpetual Office licences do not appear in your Microsoft 365 admin centre and most businesses genuinely do not know how many they have.

The two dates that matter

Microsoft has published both deadlines, and they are not the same deadline.

1 October 2026 — Publisher becomes unusable for Microsoft 365 subscribers. Microsoft’s support notice, last updated on 3 August 2026, states that Microsoft 365 subscribers will not be able to access Publisher after 1 October 2026, and will no longer be able to open or edit Publisher files in Publisher. Microsoft’s recommended action is blunt: convert your existing files to another format before that date, because after it you will not be able to open or edit them in Publisher. Microsoft has published a sample PowerShell script for bulk-exporting .pub files to PDF.

13 October 2026 — Office 2021 reaches end of support. Microsoft’s lifecycle announcement, published 22 April 2026, confirms Office LTSC 2021 reaches end of support on 13 October 2026, after which Microsoft will no longer provide technical support, bug fixes, or security updates. Microsoft’s consumer-facing notice is more direct still: support for Office 2021 ends 13 October 2026 and there will be no extension and no extended security updates.

That second phrase deserves attention, because Windows 10 conditioned everyone to expect a paid reprieve. There is no Extended Security Updates programme for Office 2021. There is no consumer bridge year. On 13 October the tap closes, and any Office vulnerability discovered after that date stays open on those machines for as long as they run.

The same 13 October date also ends support for the perpetual version of Publisher, which is why the two deadlines are tangled together in Microsoft’s own documentation. If you bought Publisher as part of a boxed Office 2021 suite, it keeps working after October but stops being patched. If you get Publisher through a Microsoft 365 subscription, it stops working on 1 October.

Who this affects, and why it hides from your licence audit

The instinctive reaction from most business owners is that this cannot possibly apply to them, because they moved to Microsoft 365 years ago. In our experience across Australian client environments, that assumption is wrong more often than it is right, and the reason is structural.

Perpetual Office licences do not appear anywhere in your Microsoft 365 admin centre. Your licence report shows subscriptions. It does not show the copy of Office Home & Business 2021 that came bundled on a laptop bought from a retailer in 2022, or the volume-licensed Office LTSC 2021 installed on the four machines in the back office when the last server was replaced. Those installations are invisible to the tool most businesses use to answer the question “what are we running?” You only find them by looking at the devices themselves.

When we do look, the same handful of machines turn up again and again:

• The reception or front-of-house PC. Bought as a complete unit with Office included, never touched since, and the machine that opens the most unsolicited attachments in the business.
• The bookkeeper’s or practice manager’s machine. Often deliberately kept on perpetual Office because a legacy accounting or practice-management add-in was fussy about versions years ago and nobody has retested it since.
• The boardroom or shared meeting-room PC. No named user, no owner, no licence line item, and therefore no one who notices it drifting out of support.
• The site or depot machine. Common in construction, agribusiness and multi-venue hospitality. Installed on-site with a perpetual licence precisely because the link was too thin for a cloud rollout at the time.
• The one machine that drives a device. A label printer, a scanner with a scan-to-Excel workflow, a signage screen, a mail-merge machine used for member renewals. These get treated as appliances rather than computers.

Not-for-profits and community organisations tend to carry more of these than commercial businesses of the same size, for an understandable reason. Grant-funded and donated hardware arrives with whatever software was on it, at whatever point the grant landed, and there is rarely a budget line for replacing software that visibly still works.

The practical point: you cannot answer this question from a spreadsheet. You need a device-level inventory. If you have managed IT, ask your provider for a report of installed Office versions across every endpoint, including any machine that is not a person’s daily laptop. If you do not have managed IT, the fastest manual check is to open Word on each machine, go to File, then Account, and read the version under Product Information. Anything that says Office 2021, Office LTSC 2021, Office Home & Business 2021 or Office Professional 2021 is on the clock.

Publisher: the 1 October cliff

Publisher is the sharper of the two problems, and it is the one large publishers have largely skipped, because in enterprise environments almost nobody uses it. In Australian small business, not-for-profits and community organisations, plenty of people do.

The files we see in .pub format across client environments are almost always the ones that matter most and are updated least: the club newsletter that goes to members quarterly, the annual report layout that gets refreshed once a year, a venue’s function pack and set menus, an op-shop’s price signage, a school or sporting association’s registration flyer, membership renewal mail-merge templates. These are documents with real institutional value and no backup format. The layout lives in the .pub file and nowhere else.

After 1 October 2026, if your Publisher came from a Microsoft 365 subscription, those files become documents you own but cannot open. That is a different and worse category of problem than an unpatched application, because it is not recoverable by paying more money later. Microsoft has been explicit that Microsoft 365 subscribers will no longer be able to open or edit Publisher files in Publisher after that date.

There are three sensible responses, and most organisations should do the first two together.

Find the files. Search for *.pub across every PC, every mapped drive, OneDrive and SharePoint. Microsoft’s own guidance suggests exactly this search. Do it before you touch anything else, because the size of the result set determines how much work the rest of this is. A small charity might have six files. A community club with a thirty-year history might have four hundred.

Convert everything to PDF. This preserves the document as it looks today and takes minutes for a small set. For a large set, Microsoft’s sample PowerShell script will bulk-export a whole directory tree. PDF gives you a permanent, readable archive. It does not give you an editable file.

Rebuild the handful you actually still edit. This is the part people underestimate. Converting a PDF to Word produces something optimised for text editing, and Microsoft warns that the layout may shift, particularly on graphics-heavy documents. For the two or three templates you genuinely update each year, budget the time to rebuild them properly in Word or PowerPoint rather than accepting a mangled conversion. Microsoft’s own mapping puts newsletters, letterheads, labels, envelopes and forms in Word, and banners, signs and posters in PowerPoint.

Our advice to clients has been to treat the rebuild as a small design job with a deadline rather than an IT task. The person who knows what the newsletter is meant to look like is usually not the person who administers the computers.

What unsupported actually costs you

The security argument for moving off Office 2021 is straightforward and worth stating plainly rather than dramatically.

Office suites are one of the most reliably attacked pieces of software in any business, because they are the software that opens files sent by strangers. Malicious documents, macro-enabled attachments and files crafted to exploit parser flaws have been a mainstay of Australian phishing campaigns for a decade. What changes on 13 October is not the attack, it is the defence: every flaw found after that date remains permanently exploitable on those machines. Attackers know end-of-support dates as well as vendors do, and unpatched Office builds age into a durable target rather than a temporary one.

The scale of the underlying risk is documented. The Australian Signals Directorate’s Annual Cyber Threat Report 2024–25 put the average self-reported cost of a cybercrime incident at $56,600 for small businesses, $97,200 for medium businesses and $202,700 for large organisations, with medium-business costs up 55 per cent year on year. ASD received more than 84,700 cybercrime reports over the same period, an average of one report every six minutes.

The Essential Eight problem

This is the part that turns a security preference into a compliance fact, and it catches Australian businesses that never think of themselves as regulated.

Maturity Level One of the ASD Essential Eight Maturity Model requires, under Patch Applications, that office productivity suites, web browsers and their extensions, email clients, PDF software and security products that are no longer supported by vendors are removed. Not patched. Not compensated for. Removed.

From 14 October 2026, a business running Office 2021 anywhere in its fleet fails that control. Maturity Level One is the baseline expectation for most Australian small and medium businesses, and it is the level that shows up in three places that cost money:

• Tender and procurement questionnaires. Government panels, larger corporate clients and NDIS and aged-care contracting increasingly ask for Essential Eight self-assessment. A confident yes on Patch Applications becomes a qualified no.
• Cyber insurance renewals. Australian insurers ask specific questions about unsupported software. Answering them incorrectly is a materially worse outcome than answering them honestly, as we covered in our guide to cyber insurance in Australia. A proposal form signed in November that says all software is vendor-supported, when four machines are running Office 2021, is a problem you have created for a future claim.
• Client and supplier due diligence. Professional services firms handling client financial or legal data are asked about this by their own clients now, not just by regulators.

There is also a privacy dimension. Australian Privacy Principle 11 requires entities to take reasonable steps to protect personal information. Knowingly running an office suite that the vendor no longer patches, on machines that hold client records, is a harder position to defend after an incident than before one.

The numbers in Australian dollars

Here is the honest comparison, using a ten-person business as the worked example. All figures exclude GST unless stated, and licensing prices move, so confirm current pricing with your provider before committing.

Option	What you get	Indicative cost, 10 staff	Supported until	Best fit
Do nothing	Office keeps opening; no patches, no support, Essential Eight ML1 failure on Patch Applications	$0 now	13 October 2026	Nobody. This is a decision to carry risk you cannot quantify.
Office Home & Business 2024 (perpetual)	Word, Excel, PowerPoint, Outlook, OneNote. One-time purchase, one PC or Mac per licence. No Publisher, no cloud services, no security stack.	AU$379 per machine, about $3,790 total	Around October 2029	Standalone or appliance-style machines, and businesses with a genuine reason to stay off subscription.
Office LTSC 2024 (volume licensing)	The on-premises path Microsoft recommends for organisations not ready to move to cloud. Priced through a reseller, not the retail store.	Quote required	Around October 2029	Air-gapped, regulated or bandwidth-constrained sites where cloud sign-in is impractical.
Microsoft 365 Business Standard	Desktop Office plus Exchange, Teams, SharePoint and OneDrive. No Intune, no Defender for Business, no Entra ID P1.	Rose about 12 per cent on 1 July 2026 from an indicative AU$19 per user per month; confirm current rate	Continuous	Businesses that already have their security stack elsewhere.
Microsoft 365 Business Premium	Business Standard plus Intune, Defender for Business and Entra ID P1. The plan that actually helps with Essential Eight.	About AU$32.90 per user per month, roughly $11,844 over three years	Continuous	Any business handling client personal, financial or health information.

Two observations most IT providers will not put in writing.

First, on raw software cost over three years, perpetual Office 2024 is cheaper than Microsoft 365 Business Premium by roughly $8,000 for a ten-person business. That is a real number and pretending otherwise insults the reader. If Office documents are genuinely all you need and your email, security and device management already come from somewhere else, buying perpetual licences is a defensible decision.

Second, for most businesses that gap is not the comparison that matters, because the two products do different jobs. The extra spend on Business Premium buys device management, endpoint protection, conditional access and identity controls that map directly onto five of the eight Essential Eight controls. If you are buying Office 2024 outright and separately paying for endpoint protection, MDM and an identity add-on, the maths inverts quickly. We wrote about what Microsoft has already folded into these plans in the June 2026 packaging update, and it is worth checking what you are paying twice for before you decide.

The third factor is the one that decides it for most of our clients: perpetual licences reset this exact problem in three years. Office 2024 support ends around October 2029. Buy perpetual now and you will run this project again before the end of the decade, on hardware that will also need replacing by then. Some businesses are entirely comfortable with that rhythm. Others would rather never think about it again.

Do not forget the hardware

Check this before you cost anything. Microsoft 365 Apps stopped receiving new features on Windows 10 in August 2026, and Windows 10 machines are on their own separate clock, which we covered in detail in our piece on Microsoft 365 apps being frozen on Windows 10. A machine still running Office 2021 in 2026 is very often a machine still running Windows 10 as well, and if that machine also cannot take Windows 11, you are not looking at a licensing decision at all. You are looking at a hardware replacement with a licence attached to it. Cost the device, not the software.

The regional wrinkle: Central West NSW and multi-site operators

We support businesses across Sydney, Brisbane, Melbourne and Central West NSW, and the Office rollout looks materially different in Orange, Bathurst and Dubbo than it does in Brookvale. This is the part of the job that generic upgrade guides get wrong, because they assume every machine sits behind a fibre connection with an engineer down the corridor.

Three practical differences we plan around every time.

Bandwidth and install order. A full Microsoft 365 Apps install is a multi-gigabyte download per machine. Pushed to a dozen machines at a regional depot or a rural showroom over a shared fixed wireless or a modest NBN service, that install competes with the point-of-sale, the payment terminal and the phones. We stagger regional deployments overnight and cache installers locally rather than letting every device pull its own copy. On a metropolitan site that precaution is unnecessary; on a Central West site it is the difference between an invisible upgrade and a day of complaints.

Nobody is walking over to fix it. When an Office upgrade breaks an add-in on a Sydney machine, someone drops in. When it breaks on a farm office outside Dubbo, you are on the phone with a person who has crops to check. That changes the sequencing: pilot on one regional machine per site first, confirm the line-of-business add-ins load, and only then push the rest. It also means backing out has to be planned before you start, not improvised afterwards.

The apps are older and stranger. Regional agribusiness, food processing and trades clients run more legacy line-of-business software with Excel and Outlook integrations than their metropolitan equivalents, often because the software is specialised and the vendor is small. Livestock and grain systems, weighbridge software, older practice-management suites: these are the things that surprise you on upgrade day. Ask the vendor about Office 2024 and Microsoft 365 Apps compatibility now, in August, while there is still time to hear an unhelpful answer and plan around it. We made a similar point about regional operational exposure when ransomware shut two Queensland sugar mills mid-harvest, and it holds here: regional operations carry more single points of failure and fewer people to absorb the disruption when one of them goes.

The same logic applies to multi-venue hospitality groups. A back-office PC at each of five venues is five separate upgrade events, five sets of till-adjacent software to verify and five managers whose Saturday you can ruin. Sequence them across quiet trading days, not all at once on the first Tuesday of October.

Your six-week action plan

Publication of this piece leaves roughly five weeks until the Publisher deadline and six until Office 2021 end of support. That is enough time if you start now, and it is not enough time if you start in the last week of September.

1. Week one: find the Publisher files. Search *.pub across all PCs, network drives, OneDrive and SharePoint. Record how many there are and who owns them. This is first because the 1 October deadline is first.
2. Week one: inventory Office versions on every device. Not just laptops. Reception, boardroom, back office, depot, the machine attached to the label printer. Ask your IT provider for a fleet-wide installed-software report if you have one.
3. Week two: convert and archive. Export every .pub file to PDF and store the PDFs somewhere backed up. Flag the two or three templates that still get edited annually for a proper rebuild in Word or PowerPoint.
4. Week two: check the hardware underneath. For every machine running Office 2021, confirm the Windows version and whether the device supports Windows 11. Machines failing both tests move to the hardware budget, not the software budget.
5. Week three: ask your line-of-business vendors. Send one email per vendor asking whether their add-in or integration is supported on Microsoft 365 Apps and Office 2024. Keep the replies. Slow vendors are the single most common cause of a stalled Office project.
6. Week three: decide and price. Perpetual, subscription or a mix. Get the quote in writing including any hardware. Approve it.
7. Week four: pilot. One machine per site, ideally including the fussiest user and the machine with the oddest attached device. Confirm add-ins, printing, scanning and any mail merge still work.
8. Weeks five and six: roll out and verify. Stagger by site and by trading day. Finish with a verification pass confirming no device still reports an Office 2021 build, and record that result. That record is what you show an insurer or a tender assessor next year.

If your fleet is under about fifteen machines and nothing exotic is attached to them, this is a few hours of work spread over a fortnight, not a project. The businesses that struggle are the ones that discover a critical add-in problem on 10 October.

Four mistakes we expect to see

Assuming Microsoft will blink. Microsoft’s own wording says there will be no extension and no extended security updates for Office 2021. Windows 10 got a paid bridge because the installed base was enormous and consumer-facing. Office 2021 will not get one. Planning on a reprieve is planning on nothing.

Buying licences before checking the hardware. Every year we see businesses purchase software for machines that need replacing within months. Confirm the device supports Windows 11 and has a sensible remaining life before you attach a licence to it.

Treating Publisher as a formality. The .pub file containing your annual report layout, your member renewal template or your venue’s function pack is not a formality. Find those files in the next fortnight, not the last week of September, because converting is quick and rebuilding is not.

Fixing the laptops and forgetting the appliances. The machine driving the label printer, the shared boardroom PC, the depot terminal and the reception computer are exactly the machines that run old Office and exactly the machines nobody owns. Build the inventory from the device list, not from the staff list.

Talk to All IT Services

If you want this handled rather than managed, we can run the whole sequence: a device-level Office inventory across your fleet, a .pub file sweep with bulk conversion, a licensing comparison priced in Australian dollars for your actual headcount, vendor compatibility checks on your line-of-business software, and a staged rollout that does not interrupt trading. For clients on managed agreements, the inventory and the Publisher sweep are part of the service.

All IT Services supports businesses across Sydney and the Northern Beaches, Brisbane, Melbourne and Central West NSW, with a particular focus on professional services, hospitality and not-for-profits. Call 1300 425 548 or get in touch here. If you would rather do it yourself, start with the .pub search this week. That is the deadline you cannot buy your way out of later.

Frequently asked questions

Can we keep using Office 2021 after 13 October 2026?

The applications will keep opening and your files will keep working. What stops is security updates, bug fixes and technical support, permanently, with no extended security updates available for purchase. The practical consequences are that any Office vulnerability discovered after 13 October 2026 stays exploitable on those machines, and that your business fails the Patch Applications control at Maturity Level One of the ASD Essential Eight, which requires unsupported office productivity suites to be removed.

What happens to our Publisher files?

If your Publisher came with a Microsoft 365 subscription, you will not be able to open or edit .pub files in Publisher after 1 October 2026. Microsoft recommends converting them to another format before that date. Export everything to PDF for the archive, and rebuild the two or three templates you still edit each year in Word or PowerPoint. If you have a perpetual boxed version of Publisher, it will keep running after October, but it stops receiving support on 13 October 2026.

Is buying Office 2024 outright cheaper than Microsoft 365?

On software cost alone over three years, yes. Office Home and Business 2024 lists at AU$379 for one PC or Mac on the Australian Microsoft Store, so a ten-person business would spend about $3,790 once, against roughly $11,844 over three years for Microsoft 365 Business Premium at about $32.90 per user per month. The comparison changes if you are separately paying for endpoint protection, device management or an identity add-on, because Business Premium includes those. Perpetual licences also reset the same end-of-support problem around October 2029.

Will running Office 2021 affect our cyber insurance or tender eligibility?

It can affect both. Australian cyber insurance proposal forms ask directly whether you run vendor-supported software, and answering that question incorrectly creates a problem at claim time rather than at renewal time. Tender and procurement questionnaires from government panels and larger corporate clients increasingly ask for Essential Eight self-assessment, and an unsupported office suite turns a clean answer on Patch Applications into a qualified one.

How long does the upgrade take for a twenty-person business?

For a straightforward fleet with no unusual add-ins, plan on two to three weeks end to end, most of which is waiting on vendor confirmations and scheduling around trading hours rather than technical work. Add time if machines need replacing, if you have multiple sites, or if a line-of-business vendor is slow to confirm compatibility. The step that most often blows out the timeline is discovering a critical add-in problem late, which is why the pilot machine matters.

Sources

• Office LTSC 2021 reaching end of support on October 13, 2026, Microsoft Lifecycle, 22 April 2026
• End of support for Office 2021, Microsoft Support
• Microsoft Publisher will no longer be supported after October 2026, Microsoft Support, updated 3 August 2026
• Office Home & Business 2024 pricing, Microsoft Store Australia, checked 26 August 2026
• Annual Cyber Threat Report 2024–25, Australian Signals Directorate
• Essential Eight Maturity Model, Australian Signals Directorate