Office Professional 2021 use in tandem with 365 - October 2026

Question

Office Professional 2021 use in tandem with 365 - October 2026

Jim Hunt 20

I'm assisting a customer who wants to continue using Publisher after it reaches the end of support in October 2026.

The customer currently has a Microsoft 365 subscription, which they need to keep for services such as 200 GB of OneDrive storage and, ideally, Copilot. They are considering purchasing Office Professional 2021 specifically to continue using the perpetual version of Publisher.

My understanding is that Office Professional 2021 and Microsoft 365 Apps are generally not intended to be installed side by side. However, I'm unsure how licensing behaves if the customer attempts to use Publisher 2021 while retaining Microsoft 365 for the other Office applications.

My concern is that the Microsoft 365 license could periodically take precedence and activate Word, Excel, Outlook, and Publisher as Microsoft 365 Apps, effectively overriding the perpetual Publisher 2021 license and stopping Publisher from working since it now thinks it is the EOL 365 version. If that happened, would the customer then need to reactivate or switch Publisher back to the Office Professional 2021 license? I am guessing this would then require downgrade versions of Word, etc., too if it updates past what 2021 allows. Or are the two licenses able to be used in tandem with each other for the different apps?

Has anyone tested this scenario, or can Microsoft confirm whether this is a supported configuration?

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Answer accepted by question author

Jade Ng 15,485 Microsoft External Staff Moderator

Dear @Jim Hunt,

Thank you for your detailed question, and I completely understand your concern.

Based on Microsoft’s current guidance, Microsoft Publisher will be retired from Microsoft 365 in October 2026, and after that date it will no longer be possible to open or edit Publisher files using the Microsoft 365 version of the app. You are correct that one potential option is to use a perpetual version of Publisher (for example, included in Office Professional 2021). That version can continue to run locally even after 2026, although it will no longer receive updates or support.

However, I would like to highlight an important limitation to avoid unexpected issues:

Microsoft 365 Apps and Office 2021 are not designed to run side-by-side on the same device when they include overlapping applications (such as Word, Excel, Outlook, and Publisher).
In most cases, installing both on the same machine leads to activation conflicts, shared installation behavior, or one version overriding the other, because they use the same underlying technology.
As a result, there is no supported configuration where Microsoft 365 Apps and Office 2021 can reliably operate independently per application (for example, using Publisher 2021 while using Office apps from Microsoft 365 on the same device).

Because of this, Microsoft does not provide a supported way to switch licensing between the two versions or isolate Publisher 2021 within a Microsoft 365 installation.

To avoid disruption, the most reliable options are:

1.Use a separate environment for Publisher (for example, a second PC, virtual machine, or isolated setup with Office 2021 installed)

2.Continue using Microsoft 365 on your primary device for:

OneDrive storage
Copilot features
Latest Office apps

This approach ensures both solutions work correctly without conflicts.

For reference: Microsoft Publisher will no longer be supported after October 2026

I hope this helps. Appreciate your patience and understanding and thank you for your time and cooperation. Please feel free to reply below if you have any update or further concern.

I am looking forward to your response!

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Jim Hunt 20 Reputation points

2026-06-29T03:04:10.4333333+00:00

Great answer. Covers exactly the knowledge gap that I had, and while the answer doesn't supply a solution to my customer's situation, it answers the question put forward well.
Jade Ng 15,485 Reputation points Microsoft External Staff Moderator

2026-06-29T05:22:14.7966667+00:00

Dear @Jim Hunt,

Thank you for your response!

I really appreciate your feedback and I’m glad the explanation helped clarify things.

If you encounter any other issues, please feel free to post a new question so other moderators can help, or tag me so I can continue supporting you in the future.

Thank you very much for your valuable time and your cooperation. Hope you having a nice day and really much warm regards to you as well!
Michele Abbasciano 0 Reputation points

2026-09-11T16:25:34.78+00:00

Dear @Jade Ng,

Thank you very much for the detailed and helpful response.

I would like to ask a more specific follow-up question regarding a potential alternative setup.

If the user maintains their current Microsoft 365 subscription (which does not include Publisher) for Word, Excel, Outlook, OneDrive, and Copilot, but purchases and installs the standalone, standalone/perpetual version of Microsoft Publisher 2021 (the single-app standalone license, rather than the full Office Professional 2021 suite), would they still encounter the same licensing and activation conflicts?

Since Publisher 2021 standalone would be installed as an individual app alongside Microsoft 365, without any other overlapping applications (like Word or Excel from the perpetual suite), is this considered a supported or functional configuration? Or does the underlying Click-to-Run deployment architecture still cause activation or technology conflicts between the Microsoft 365 suite and the standalone 2021 app?

Thank you again for your time, assistance, and expertise.

Best regards,
Jade Ng 15,485 Reputation points Microsoft External Staff Moderator

2026-09-14T04:04:17.6066667+00:00
Hi Michele,

Thank you for your question.

Based on the information provided, installing a standalone perpetual license of Microsoft Publisher 2021 alongside an existing Microsoft 365 subscription is generally expected to work, provided that only Publisher is being installed and not a full perpetual Office suite that includes overlapping applications such as Word, Excel, or Outlook.

The main concern in mixed Office deployments is typically related to duplicate Office applications rather than Publisher itself. When multiple versions of core Office apps are installed, activation, file associations, updates, and product licensing behavior can become more complex. However, if Publisher 2021 is installed as a standalone application while Microsoft 365 continues to provide Word, Excel, Outlook, OneDrive, and Copilot functionality, the risk of licensing or activation conflicts is significantly lower.

Publisher 2021 and Microsoft 365 both utilize Microsoft's Click-to-Run deployment technology, which generally supports coexistence scenarios when the installed products do not overlap. For that reason, a standalone Publisher installation is typically a more straightforward configuration than installing a complete Office 2021 suite alongside Microsoft 365.

As a best practice, I recommend verifying that:

Microsoft 365 applications remain activated after Publisher is installed.

Publisher 2021 activates successfully with its standalone license.

Copilot and other Microsoft 365 features continue to function as expected in the Microsoft 365 applications.

If this deployment will be used in a production environment, I recommend testing the configuration on a single device first before broader deployment.

I hope this helps clarify the scenario.

1 additional answer

Your answer

Jim Hunt 20 Reputation points

2026-06-29T03:04:10.4333333+00:00

Great answer. Covers exactly the knowledge gap that I had, and while the answer doesn't supply a solution to my customer's situation, it answers the question put forward well.
Jade Ng 15,485 Reputation points Microsoft External Staff Moderator

2026-06-29T05:22:14.7966667+00:00

Dear @Jim Hunt,

Thank you for your response!

I really appreciate your feedback and I’m glad the explanation helped clarify things.

If you encounter any other issues, please feel free to post a new question so other moderators can help, or tag me so I can continue supporting you in the future.

Thank you very much for your valuable time and your cooperation. Hope you having a nice day and really much warm regards to you as well!
Michele Abbasciano 0 Reputation points

2026-09-11T16:25:34.78+00:00

Dear @Jade Ng,

Thank you very much for the detailed and helpful response.

I would like to ask a more specific follow-up question regarding a potential alternative setup.

If the user maintains their current Microsoft 365 subscription (which does not include Publisher) for Word, Excel, Outlook, OneDrive, and Copilot, but purchases and installs the standalone, standalone/perpetual version of Microsoft Publisher 2021 (the single-app standalone license, rather than the full Office Professional 2021 suite), would they still encounter the same licensing and activation conflicts?

Since Publisher 2021 standalone would be installed as an individual app alongside Microsoft 365, without any other overlapping applications (like Word or Excel from the perpetual suite), is this considered a supported or functional configuration? Or does the underlying Click-to-Run deployment architecture still cause activation or technology conflicts between the Microsoft 365 suite and the standalone 2021 app?

Thank you again for your time, assistance, and expertise.

Best regards,
Jade Ng 15,485 Reputation points Microsoft External Staff Moderator

2026-09-14T04:04:17.6066667+00:00

Hi Michele,

Thank you for your question.

Based on the information provided, installing a standalone perpetual license of Microsoft Publisher 2021 alongside an existing Microsoft 365 subscription is generally expected to work, provided that only Publisher is being installed and not a full perpetual Office suite that includes overlapping applications such as Word, Excel, or Outlook.

The main concern in mixed Office deployments is typically related to duplicate Office applications rather than Publisher itself. When multiple versions of core Office apps are installed, activation, file associations, updates, and product licensing behavior can become more complex. However, if Publisher 2021 is installed as a standalone application while Microsoft 365 continues to provide Word, Excel, Outlook, OneDrive, and Copilot functionality, the risk of licensing or activation conflicts is significantly lower.

Publisher 2021 and Microsoft 365 both utilize Microsoft's Click-to-Run deployment technology, which generally supports coexistence scenarios when the installed products do not overlap. For that reason, a standalone Publisher installation is typically a more straightforward configuration than installing a complete Office 2021 suite alongside Microsoft 365.

As a best practice, I recommend verifying that:

Microsoft 365 applications remain activated after Publisher is installed.

Publisher 2021 activates successfully with its standalone license.

Copilot and other Microsoft 365 features continue to function as expected in the Microsoft 365 applications.

If this deployment will be used in a production environment, I recommend testing the configuration on a single device first before broader deployment.

I hope this helps clarify the scenario.

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