Microsoft 365 vs Office 2021: which should you choose?

The core difference: a subscription versus a one-off purchase

Microsoft 365 and Office 2021 give you the same familiar applications, but you pay for and use them in a fundamentally different way. Microsoft 365 is a subscription: you pay monthly or yearly and keep access to the apps, cloud storage and ongoing updates. Office 2021 is a one-off purchase, also called a perpetual licence: you pay once and can keep using the 2021 version, even years later, but without new features.

That single choice drives almost all the other differences: how pricing works, whether you get new features, how many devices you can use and how much storage is included. In the rest of this article we run through those points so you can choose based on your own usage rather than on which package is supposedly "better". Both are full Office suites; they simply suit different working patterns. Microsoft also sets out the differences in its official comparison of Microsoft 365 and Office 2021.

Price and payment model differ sharply

Microsoft 365 Personal costs around €69 per year for one person; the Family version costs around €99 per year for up to six people, each with their own storage and settings. You pay continuously, and as long as your subscription is active you have the latest version. If you stop paying, the desktop apps fall back to a read-only mode where you can still open and print files, but no longer edit them.

Office 2021 requires a one-off payment. The home version Home & Student costs around €149 and includes Word, Excel and PowerPoint. You pay that amount once and there are no subscription costs, regardless of how long you use the software.

When you work out which is cheaper, weigh up how many years you want to keep the same version. A simple calculation: at around €69 per year, you have matched the purchase price of a Home & Student licence after just over two years. If you use an Office suite for five years, a subscription costs considerably more, but in return you get new features every year, more devices and cloud storage. For a family, the calculation shifts: the Family version spreads the cost across up to six people, which often works out cheaper per person than six separate purchases.

With the subscription you also have a choice in payment frequency. Paying monthly costs slightly more per month, but you can cancel at any time. Paying yearly gives a lower monthly price, but commits you for a year. If you need Office only temporarily, for example for a single project lasting a few months, a monthly subscription can sometimes cost less than a one-off purchase because you stop as soon as you are finished.

Features and updates: constantly refreshed or frozen

With Microsoft 365, new features arrive regularly alongside security updates and bug fixes. Your apps keep pace with what Microsoft releases, including new collaboration and AI features that only appear in the subscription version. Office 2021 stays fixed at the features from its release year. It does receive security updates, but no new capabilities.

That difference matters especially if you want to rely on new features. If you want a stable, unchanging environment with no surprises after an update, a fixed version can actually be the better option because the interface and behaviour stay the same for years. In managed environments, that predictability is a reason to choose a perpetual licence deliberately, because an administrator does not have to keep testing or explaining new features.

You sometimes notice the feature difference in formulas. If you run into new dynamic array behaviour in Excel, our explanation of the Excel #SPILL! error can help, because that only occurs with the newer formula engine. Features like this arrive first in Microsoft 365 and only later, or not at all, in a fixed version. If you depend on the very latest features for work, a frozen version can hit limits that only disappear with the next purchase.

Devices and storage: multiple devices or a single device

Microsoft 365 can be installed on multiple devices, including PCs, Macs, tablets and phones, and you can be signed in on up to five devices at the same time. Personal and Family include 1 TB of OneDrive cloud storage per person, plus extra security features in Outlook and OneDrive. For a family on the Family plan, that means six times 1 TB, divided among the members, each with their own sign-in and their own files.

Office 2021 is tied to one PC or Mac and does not include cloud storage. You keep files locally or in your own storage solution. If you work on a single device and do not need to sync with the cloud, that is no loss. If you regularly switch between a laptop, tablet and phone, installation on multiple devices is one of the strongest arguments for the subscription, because you start on one device and carry on seamlessly on another.

The 1 TB of OneDrive storage does more than store files. It automatically backs up your documents, keeps older versions so you can undo a change, and syncs settings between devices. If your laptop is lost or breaks, your files are still in the cloud. If you do not have your own backup solution, the subscription immediately gives you a safety net that is completely absent with Office 2021.

Which apps are included in each package

The content differs by edition. Pay particular attention to Outlook, which is not included in every Office 2021 home version, and to the business apps that only appear in certain editions.

• Microsoft 365 Personal and Family: Word, Excel, PowerPoint, Outlook and OneNote, with cloud features and OneDrive storage.
• Office 2021 Home & Student: Word, Excel, PowerPoint and OneNote, without Outlook.
• Office 2021 Home & Business: the same apps plus Outlook, aimed at self-employed professionals and small businesses.

The free web versions of Word, Excel and PowerPoint can always be used with a Microsoft account, albeit with fewer features than the desktop apps. For light use, those web apps are sometimes sufficient, which saves you money. If you need Outlook, check carefully which edition you buy, because the cheapest home version of Office 2021 does not include it and you would then still need a separate Outlook purchase or upgrade.

Alongside the home versions, there are business Microsoft 365 subscriptions such as Business Basic, Business Standard and Business Premium. Business Basic offers only the web and mobile apps plus business email through Exchange; Business Standard adds the full desktop apps. For a sole trader or small team, whether you need the desktop programs mainly determines which of these two suits you. These business subscriptions are charged per user per month and include management features that the home versions lack.

Security and collaboration matter in your choice

Besides features and price, what you get for security and collaboration also differs. Microsoft 365 includes continuous security updates for as long as your subscription runs, plus extra protection in Outlook and OneDrive, such as encrypted attachments and a vault for sensitive files. Because the apps are constantly updated, Microsoft closes new vulnerabilities without you having to buy anything.

Office 2021 receives security updates until the end date in October 2026, but no new protection features. After that date, the suite receives no more patches, which makes it more vulnerable over time to newly discovered flaws. If you work with sensitive data, that support window is a genuine consideration.

For collaboration, Microsoft 365 leans heavily on the cloud: several people can edit the same document at the same time through OneDrive, with automatic versions and comments in real time. Office 2021 can also share files, but lacks the smooth simultaneous editing that the subscription version offers in the cloud. If you often work together on the same files, that difference carries real weight.

A practical consequence of that cloud model is that you send files back and forth less often. Instead of emailing a document and later merging versions, you share a link and everyone works in the same file. That avoids the familiar situation where three people each have their own version and nobody knows which is the latest. If you work alone, you do not miss that benefit and the simplicity of a local file is often enough.

Microsoft 365 and Office 2021 side by side

When to choose Microsoft 365 and when to choose Office 2021

The choice depends on how you use the software, not on which package is "better". The guidelines below help you decide.

• Choose Microsoft 365 if you work on multiple devices, want cloud storage, expect the latest features, share with several people or need Outlook and collaboration features.
• Choose Office 2021 if you work on a single PC, prefer to pay once, do not need the cloud and are happy with a stable, unchanging version for a few years.

Two concrete situations make the difference tangible. A student who works with Word and Excel on a single laptop for four years is often better off with Office 2021 Home & Student, provided they keep an eye on the end date. A family with children who work on multiple devices and want to store photos gets more value from Microsoft 365 Family, thanks to six users and six times 1 TB of storage. The right choice therefore follows from how many people, how many devices and how many years you put into the calculation.

There is also a middle ground: use the free web apps for light work and buy a fixed version only if you regularly work offline and need advanced features. For shared presentations and documents, it also matters whether your formatting looks right everywhere. If you share many PowerPoint files, make sure you embed fonts in PowerPoint, whichever Office version you choose, because that problem affects both versions and has nothing to do with your licence.

Switching between the two is possible but is not an upgrade

If you want to move from a fixed version to a subscription, you simply buy a Microsoft 365 subscription and install the apps again; your files remain the same because the format is identical. The reverse is also possible: you cancel the subscription and buy a fixed version. In both cases you open the same .docx, .xlsx and .pptx files without conversion.

What does not exist is a discount to "upgrade" from Office 2021 to Office 2024 or to a subscription. A new fixed version is bought at full price; there is no upgrade path with a trade-in. Bear that in mind if you are considering Office 2021 shortly before the end date: you will pay the full price again for a successor. If you want to avoid that prospect, a subscription is the better route, because the successor is always included.

When switching to a fixed version, it is wise to check your files in advance for features that only the subscription knows. A workbook with a formula that relies on the latest Excel engine may behave differently in an older fixed version. In that case, test your most important documents in the new environment before you finally cancel the subscription so you do not get any surprises.

Lifespan and support determine how long it lasts

Office 2021 is supported until 13 October 2026. Until that date you receive security updates; after that support stops and the suite no longer receives patches. If you want a purchase to last for years, that end date is an important factor, especially if you are only now considering buying and therefore have a limited support window left.

If you want a new fixed version after 2026, Office 2024 is the successor as a one-off purchase, with its own support window. Office 2024 is also a frozen version without ongoing feature updates, so the distinction from a subscription remains the same: a fixed version gives you stability and a one-off price, while a subscription gives you continuous improvement at a recurring price.

Microsoft 365 has no fixed end date: as long as you pay for the subscription, it remains updated and supported. So weigh the end date of the fixed version together with the yearly price and the number of devices you use. If you value certainty about years of updates, choose the subscription; if you want a predictable, one-off spend, choose the fixed version. Both choices are defensible; let the deciding factors be how many devices and people you support and whether continuous change adds value for you or simply creates uncertainty.