Office 2021 vs Microsoft 365 in 2026: Which Is Right for Your Business?

If your business is still using Office 2021, an important deadline is approaching.

Microsoft ends support for Office 2021 on 13 October 2026.

After that date, Word, Excel, Outlook and the other Office 2021 applications may continue to work, but Microsoft will stop providing security updates, bug fixes and technical support. Microsoft has also confirmed that there will be no extension and no Extended Security Updates programme for Office 2021.

For businesses, that makes the comparison between Office 2021 and Microsoft 365 much more important than it was a few years ago.

The question is no longer simply whether you prefer buying software outright or paying a subscription.

It is increasingly about whether your business wants to continue using a fixed, ageing Office platform or move to a continually supported Microsoft 365 environment.

What Is Office 2021?

Office 2021 is a traditional perpetual version of Microsoft Office.

A business purchases the licence and installs the applications on a supported computer.

Depending on the edition, this can include familiar applications such as:

• Word
• Excel
• PowerPoint
• Outlook

The attraction is straightforward: rather than paying an ongoing subscription, you pay for the software once.

However, Office 2021 is essentially a fixed product.

It receives security and reliability updates while Microsoft supports it, but it does not continually gain the major new functionality delivered through Microsoft 365.

And now its support lifecycle is almost over.

What Happens to Office 2021 After 13 October 2026?

Office 2021 will not suddenly stop opening on 14 October.

Your Word documents will not disappear.

Excel will not stop calculating formulas overnight.

But the applications will become unsupported.

That means Microsoft will no longer provide:

• security updates
• bug fixes
• technical support
• fixes for newly discovered vulnerabilities

For a home computer, some people may choose to accept that risk.

For a business processing customer information, financial data, email and commercially sensitive documents, continuing indefinitely with unsupported software is much harder to justify.

Unsupported applications can also create problems for organisations working towards cybersecurity standards or operating in regulated sectors.

What Is Microsoft 365?

Microsoft 365 is Microsoft's subscription-based productivity platform.

Instead of buying a fixed version of Office and replacing it every few years, businesses pay a recurring subscription for continually updated software and cloud services.

Depending on the licence selected, Microsoft 365 can include:

• Word
• Excel
• PowerPoint
• Outlook
• Exchange Online
• OneDrive
• SharePoint
• Microsoft Teams
• Microsoft Intune
• Microsoft Defender for Business
• Microsoft Entra ID
• Microsoft Defender for Office 365
• security and compliance features

This is why Microsoft 365 should not simply be thought of as Office paid monthly.

For many businesses, it becomes part of the wider IT platform.

Office 2021 vs Microsoft 365: What's the Main Difference?

The simplest way to think about it is:

Office 2021 is a fixed software purchase.

Microsoft 365 is an ongoing service.

Office 2021 gives you a particular generation of applications.

Microsoft 365 gives you supported Office applications plus additional cloud, collaboration and security services depending on the subscription.

Microsoft continues to describe its perpetual Office products as one-time purchases, while Microsoft 365 is a subscription designed to remain continually updated.

Security

This is now one of the biggest reasons for businesses to review Office 2021.

Office 2021 stops receiving security updates after 13 October 2026.

Microsoft 365 Apps, by comparison, are continuously maintained while used within a supported Microsoft 365 environment.

That does not mean simply buying Microsoft 365 makes your business secure.

You still need to configure important controls such as:

• multi-factor authentication
• Conditional Access
• endpoint security
• secure sharing
• administrator permissions
• device management
• email protection
• patch management

But running supported software removes one unnecessary source of risk.

New Features

Office 2021 largely remains the product you originally purchased.

You receive security and maintenance updates during the supported lifecycle, but it does not continually evolve into newer generations of Office.

Microsoft 365 Apps receive ongoing feature improvements.

That can include updates to:

• Word
• Excel
• Outlook
• PowerPoint
• collaboration
• accessibility
• cloud integration
• administration
• AI-powered functionality

For many businesses, this means users can benefit from improvements without waiting several years for the next major Office upgrade.

Outlook and Business Email

One common point of confusion is the difference between Outlook and email hosting.

Outlook is an email application.

Exchange Online is Microsoft's cloud email service.

Buying Office 2021 does not automatically give a business an Exchange Online mailbox.

Microsoft 365 business plans can combine the Outlook application with Exchange Online, giving businesses professional email, calendar services and central administration.

That can make Microsoft 365 significantly more valuable than simply comparing the cost of desktop applications.

OneDrive

Many Microsoft 365 business plans include OneDrive cloud storage.

This allows users to store their working files within Microsoft 365 and access them from approved devices.

Used correctly, OneDrive can provide benefits such as:

• access from multiple locations
• document versioning
• easier laptop replacement
• collaboration
• controlled file sharing
• reduced dependence on files stored only on one computer

Office 2021 itself does not provide that wider cloud platform.

SharePoint

SharePoint provides shared storage and collaboration for teams and departments.

Instead of important business documents sitting on an old file server or inside one employee's personal folder structure, SharePoint can provide centrally managed document libraries with permissions, version history and Microsoft 365 integration.

For many businesses, SharePoint and OneDrive together represent a significant change in how information is stored and managed.

Microsoft Teams

Microsoft Teams can provide:

• instant messaging
• online meetings
• video calls
• shared channels
• file collaboration
• internal communication
• application integration

Availability depends on the particular Microsoft 365 licensing arrangement, so businesses should check what is included before purchasing.

But for organisations already using Teams heavily, comparing Microsoft 365 with Office 2021 purely on Word and Excel misses much of the value.

Working Across Multiple Devices

Modern employees frequently work from more than one location.

They may use:

• an office PC
• a laptop
• a home-working setup
• a mobile phone
• a tablet
• another company location

Microsoft 365 is designed around this modern user-based model.

That generally makes it more appropriate for hybrid and remote working than a traditional Office licence tied to one machine.

Device Management

Microsoft 365 Business Premium includes Microsoft Intune Plan 1, allowing organisations to centrally manage supported devices.

Depending on how it is configured, Intune can help businesses:

• enrol laptops and mobile devices
• apply security settings
• deploy applications
• manage compliance
• control access to company information
• protect company data on personal devices
• remotely remove corporate information

For a business with remote workers or a growing number of laptops, this can significantly improve visibility and consistency.

Endpoint Protection

Microsoft 365 Business Premium also includes Microsoft Defender for Business. Microsoft positions it as an endpoint-security solution for small and medium-sized organisations and includes capabilities beyond traditional antivirus.

This can give businesses additional protection against threats such as:

• malware
• ransomware
• compromised endpoints
• suspicious activity
• attacks targeting user devices

Again, the important point is that these features need to be configured and monitored properly.

Licensing a security tool and actually managing it effectively are two different things.

Microsoft 365 Business Standard vs Business Premium

For many SMEs, the choice eventually comes down to Business Standard or Business Premium.

Business Standard is generally aimed at organisations that primarily need productivity, business email and collaboration.

Business Premium adds stronger identity, endpoint and device-management capabilities.

Microsoft currently lists Business Premium as including desktop Office applications, business email, 1 TB of cloud storage per user and security capabilities involving Intune and Defender.

For organisations that want Microsoft 365 to form part of their wider cybersecurity strategy, Business Premium is often worth serious consideration.

That does not mean every business automatically needs it.

The correct licence depends on what you actually intend to use.

What About Office 2024?

Microsoft 365 is not the only replacement for Office 2021.

Businesses that still prefer perpetual licensing can consider Office 2024.

Office 2024 is another one-time purchase.

You pay upfront and receive a fixed generation of Office applications for a computer. It does not include the same ongoing cloud services and continuous feature additions associated with Microsoft 365.

For some organisations, that may still make sense.

Examples could include:

• isolated computers
• specialist workstations
• environments with limited internet connectivity
• systems designed to perform one specific function
• organisations that deliberately minimise software changes

For the average cloud-connected business, however, Microsoft 365 will usually provide a broader platform.

Is Microsoft 365 More Expensive?

A Microsoft 365 subscription creates an ongoing monthly or annual cost.

That can make Office 2021 appear cheaper if you compare only the licence cost.

But businesses should compare the whole environment.

Consider whether you separately need:

• email hosting
• cloud storage
• Teams
• endpoint protection
• device management
• identity controls
• collaboration platforms
• remote-working tools

If those services would otherwise be purchased separately, the comparison changes significantly.

The cheapest licence is not automatically the lowest-cost IT strategy.

What About AI and Copilot?

Microsoft's productivity platform is also increasingly incorporating AI.

Microsoft 365 Copilot and related AI functionality can assist with tasks such as:

• summarising information
• drafting documents
• analysing data
• preparing meetings
• reviewing email
• creating presentations

Availability and licensing vary, and Copilot should not be the sole reason to migrate from Office 2021.

But businesses planning their technology strategy for the next several years should recognise that Microsoft's future development is increasingly centred around Microsoft 365 rather than older perpetual Office products.

Which Is Better for Small Businesses?

For most modern small and medium-sized businesses, Microsoft 365 is likely to be the stronger long-term option.

That is particularly true if the organisation needs:

• business email
• remote working
• shared documents
• cloud storage
• Teams
• device management
• stronger cybersecurity controls
• simple user onboarding and offboarding

Office 2024 may still have a place where a business only requires desktop applications and deliberately wants a perpetual licensing model.

Office 2021, however, is now approaching the end of the road.

What Should Businesses Using Office 2021 Do Now?

If you still use Office 2021, start by finding out where it is installed.

Do not assume every computer in the company runs the same version.

1. Create a Software Inventory

Identify every device running Office 2021.

2. Check the Windows Version

Many businesses still running Office 2021 may also have ageing Windows PCs.

Windows 10 itself reached end of support on 14 October 2025, so some organisations may need to address both Office and Windows at the same time.

3. Review Existing Microsoft Licences

You may already be paying for Microsoft 365 licences that include desktop applications.

Check before buying anything else.

4. Check Add-ins and Integrations

Review anything that connects to Office, including:

• Outlook plugins
• Excel add-ins
• macros
• Access databases
• document-management software
• CRM integrations
• accounting applications
• specialist templates

5. Decide Between Office 2024 and Microsoft 365

Choose based on actual business requirements rather than simply replacing Office 2021 with the closest-looking product.

6. Test Before Wider Deployment

Move a small group of representative users first.

Check important documents, macros, email integrations and specialist applications.

7. Roll Out in Stages

A staged migration makes problems much easier to identify and correct.

Don't Wait Until October

The deadline is 13 October 2026.

Businesses now have only a short period to prepare.

Leaving the decision until the final week increases the likelihood of discovering problems at exactly the wrong time.

Older PCs, unsupported Windows versions, Outlook plugins, spreadsheets full of macros and legacy software can all complicate an Office migration.

Finding those issues now gives you time to deal with them properly.

How Hamilton Group Can Help

Hamilton Group can help businesses review their existing Microsoft environment and create a practical migration plan before Office 2021 support ends.

We can assist with:

• identifying Office 2021 installations
• Microsoft 365 licensing
• Microsoft 365 migrations
• Office application deployment
• Exchange Online
• OneDrive
• SharePoint
• Microsoft Teams
• Microsoft Intune
• Microsoft Defender for Business
• Microsoft 365 security
• Windows 11 migrations
• device replacement planning
• ongoing Microsoft 365 support

The aim should not simply be to replace one Office licence with another.

It is an opportunity to make sure your business is using a supported, secure and properly managed productivity platform.

If you're still running Office 2021, now is the time to decide what replaces it before support ends on 13 October 2026.

Visit hgmssp.com or call 0330 043 0069 to speak with Hamilton Group about Office 2021, Microsoft 365 and your migration options.