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For years, accounting firms using Thomson Reuters Virtual Office CS could access their CS Professional Suite applications, Microsoft Office tools, email, calendars, and files within one hosted environment.
That arrangement is now changing. Thomson Reuters is discontinuing its Hosted Exchange service for Virtual Office CS and Software-as-a-Service customers on August 31, 2026. Firms will need to move their email data to Microsoft 365 or another provider and assume greater responsibility for licensing and administering their Microsoft environment.
Virtual Office CS itself is not being discontinued. Applications such as UltraTax CS, Accounting CS, Practice CS, Fixed Assets CS, and FileCabinet CS can continue to operate in the Thomson Reuters environment.
What is ending is the Microsoft email service that many firms have relied on as part of that environment.
For accounting firms, the distinction matters. This is not an application shutdown, but it is more than a routine licensing update. It changes who owns and manages an important part of the firm’s technology stack.
Related Reading: Virtual Office CS vs UltraTax Cloud Hosting
Why Is Thomson Reuters Making This Change?
Thomson Reuters has not described the transition as an end to Virtual Office CS. It has positioned it as part of a broader effort to modernize its hosted infrastructure.
The company has been moving Virtual Office CS and SaaS users from an older Citrix-based environment to Azure Virtual Desktop. According to Thomson Reuters, the newer architecture provides greater flexibility to scale capacity during periods of high demand, including tax season.
The Microsoft 365 change also reflects the way Microsoft now licenses Office applications in shared and virtual environments.
Instead of Thomson Reuters supplying and managing Office and Hosted Exchange as part of the platform, each firm must now obtain supported Microsoft 365 licenses and maintain its own Microsoft tenant.
Thomson Reuters will continue to host the Microsoft Office applications within Virtual Office CS. Still, ownership and administration of the Microsoft environment will reside with the accounting firm or its chosen Microsoft Cloud Solution Provider.
What Exactly Is Stopping?
The following services and arrangements are changing:
Thomson Reuters Hosted Exchange
Thomson Reuters will no longer host or support Exchange email for Virtual Office CS and SaaS firms after August 31, 2026.
The company has already stopped creating new email domains in these environments. Firms may create email addresses under existing domains only until Hosted Exchange support ends.
Thomson Reuters-Provided Microsoft Office Licensing
Firms must bring their own supported Microsoft 365 licenses. Microsoft 365 Business Basic and Business Standard do not support the shared computer activation required for the Virtual Office CS environment. Supported options include plans such as Microsoft 365 Business Premium, E3, E5, or Microsoft 365 Apps for Enterprise, depending on the firm’s requirements.
Thomson Reuters Management of the Microsoft Environment
The firm or its Microsoft provider becomes responsible for:
- Microsoft 365 tenant administration
- User accounts and sign-in credentials
- Exchange mailboxes
- Spam and email security configuration
- Email aliases and groups
- Retention policies
- Compliance settings
- DNS and mail records
- SPF, DKIM and DMARC configuration
Thomson Reuters will continue to provide access to hosted Office applications inside Virtual Office CS, but it will not administer the firm’s Microsoft 365 tenant.
Will Firms Still Be Able to Access Their Thomson Reuters Applications?
Yes. The retirement of Hosted Exchange does not mean that UltraTax CS, Practice CS, Accounting CS, FileCabinet CS, Fixed Assets CS, Planner CS, or other CS Professional Suite applications will suddenly stop working.
Firms remaining on Virtual Office CS should continue to access their licensed Thomson Reuters applications through the hosted environment.
However, Microsoft Office functionality may be disrupted when the firm’s environment is upgraded if supported Microsoft 365 licenses have not been assigned.
Without the appropriate license, users may be unable to:
- Create or edit Excel workbooks
- Use Word and other Office applications
- Send or receive email through Outlook
Access other Microsoft productivity features inside the environment
Each user will also need to authenticate using individual Microsoft 365 credentials when accessing Office applications in Virtual Office CS.
What Happens to Existing Email, Calendars and Contacts?
Thomson Reuters is offering a managed migration service at no additional charge for firms moving their Hosted Exchange data to Microsoft 365. The managed migration includes:
- Individual mailboxes
- Shared and resource mailboxes
- Existing email messages
- Deleted-item folders
- Email folder structures
- Calendar appointments and meetings
- Calendar permissions
- Contacts
- Tasks
- Most inbox rules
Some items require manual attention after migration. Email signatures are not transferred automatically. Distribution lists must be recreated, and certain shared mailbox, calendar, formatting, or user-specific settings may need to be reconfigured.
Firms can also work with their own Microsoft Cloud Solution Provider. Thomson Reuters permits approved migration tools to connect through Exchange Web Services, although the outside provider may charge for the migration.
The point is simple: mailboxes left in Hosted Exchange will not remain available indefinitely.
If the firm does not migrate or retain them, Thomson Reuters says those mailboxes will be deleted when Hosted Exchange sunsets on August 31, 2026.
What Options Do Accounting Firms Have?
This change gives firms three practical paths. These are:
Option 1: Stay on Virtual Office CS and Manage Microsoft 365 Separately
A firm can continue using Virtual Office CS for its Thomson Reuters applications while purchasing supported Microsoft 365 licenses.
The firm must then manage Microsoft 365 internally or appoint a Cloud Solution Provider to administer it.
This may be the least disruptive route for firms that are satisfied with Virtual Office CS and have access to capable internal IT resources.
But it also divides responsibility. Thomson Reuters manages the hosted application environment, while the firm or another provider manages Microsoft 365, email security, user administration, and related configurations.
When a problem involves both systems, firms may need to determine which provider is responsible for the issue before it can be resolved.
Option 2: Keep Virtual Office CS but Use a Managed Microsoft Provider
Firms that do not want to administer Microsoft 365 themselves can work with a managed service provider.
The provider can help with licensing, mailbox migration, user provisioning, DNS configuration, spam filtering, retention, MFA, and ongoing Microsoft support.
This allows the firm to remain on Virtual Office CS while outsourcing the new responsibilities created by the transition.
Option 3: Move the CS Professional Suite to a Managed Cloud Environment
The third option is to move firm-owned, properly licensed Thomson Reuters desktop applications to a managed cloud hosting provider such as Ace Cloud Hosting.
Under this model, the firm continues to license its software from Thomson Reuters, but the applications, Microsoft 365 tools, supported third-party software, and firm data can be managed in a more unified environment.
This approach may appeal to firms that were already reviewing Virtual Office CS because of performance, application restrictions, support coordination, customization requirements, or the need to run Thomson Reuters applications alongside tools from other vendors.
The Hosted Exchange deadline does not force a firm to leave Virtual Office CS. It does, however, create a logical point for evaluating whether the existing arrangement still fits the practice.
Migrate your Thomson Reuters applications, email environment, and Microsoft 365 tools with expert support from Ace Cloud Hosting.
How Ace Cloud Hosting Can Support the Transition
Ace Cloud Hosting is a managed hosting provider for tax and accounting applications, including firm-owned Thomson Reuters software such as UltraTax CS and other applications within the CS Professional Suite.
As a Microsoft partner, Ace Cloud Hosting can also help firms obtain genuine Microsoft 365 licenses and configure Microsoft applications within the hosted environment.
Instead of managing tax software, Microsoft applications, firm data, and third-party tools across separate platforms, accounting firms can bring supported applications into a single centralized cloud workspace.
Depending on the firm’s requirements, Ace Cloud Hosting can assist with:
- Hosting properly licensed Thomson Reuters applications
- Migrating application data, files, and user environments
- Configuring Microsoft 365 applications
- Providing secure multi-user remote access
- Delivering enterprise-grade security with multi-factor authentication (MFA), end-to-end encryption, firewalls, and continuous monitoring
- Hosting QuickBooks, Sage, and other supported accounting applications alongside the CS Professional Suite
- Configuring user permissions and access controls
- Managing the underlying cloud infrastructure
- Supporting 45-day automated backups, business continuity, and disaster recovery requirements
- Scaling resources as staffing and busy-season workloads change
This approach can give firms greater flexibility over their application environment while reducing the need to coordinate multiple providers for hosting, Microsoft applications, access management, and infrastructure support.
Firms remain responsible for maintaining valid Thomson Reuters software licenses. Ace Cloud Hosting manages the underlying hosting environment and helps coordinate the migration, setup, and ongoing management of supported applications and data.
Planning your move from Virtual Office CS or Hosted Exchange? Book a free trial or speak with an Ace Cloud Hosting solution consultant to review your applications, Microsoft 365 licensing requirements, integrations, performance needs, and migration options.
Bring your CS Professional Suite, Microsoft 365 applications, firm data, and supported accounting software into one secure, managed cloud workspace.
