EPC Group says it has completed 216 Microsoft 365 tenant migrations

EPC Group says it handled 216 Microsoft 365 tenant-to-tenant migrations from 2023 to 2025, moving 1.83 million users with an average five-day cutover. The Houston consultancy also outlined how it handles Google Workspace, hybrid, GCC and GCC High migrations as enterprises face mergers, divestitures and government-cloud constraints.

Why it matters: - Microsoft 365 tenant migrations can determine whether a merger, acquisition or divestiture has a clean Day One or a broken one. - EPC Group is positioning itself as a specialist for the parts Microsoft’s native tools do not fully cover, especially coexistence, Teams, devices and regulated environments. - The firm says its playbook is designed to reduce cutover risk when organizations move mail, identity, files and security settings between tenants.

What happened: - EPC Group said it completed 216 Microsoft 365 tenant-to-tenant migrations between 2023 and 2025. - The firm said those projects moved 1.83 million users. - EPC Group said its average cutover window was five days, measured from the go-live decision to users working in the destination tenant. - The company also said it delivered more than 45 integrations for private-equity-backed portfolio companies. - EPC Group said it completed consolidation programs involving 19 or more legal entities in a single target tenant. - The firm said it completed more than 50 Microsoft 365 GCC High migrations in the past 12 months.

The details: - EPC Group said it handles tenant-to-tenant migrations after mergers and acquisitions, many-entities-to-one-tenant consolidations, Google Workspace to Microsoft 365 moves, hybrid and on-premises migrations, and moves into Microsoft 365 GCC and GCC High. - The firm also runs tenant-to-tenant migrations inside GCC High and rebrands or domain changes where the tenant stays in place. - In a tenant-to-tenant migration, EPC Group says it moves identity first, content second and endpoints last. - The migration scope includes accounts, groups, guest access, sign-in methods, mailboxes, archives, OneDrive, SharePoint, Teams, applications, security controls and devices. - EPC Group says coexistence is the period when both tenants stay live and users in each must work as one company. - The firm said coexistence problems, not data transfer problems, create many Day One complaints. - For Google Workspace to Microsoft 365 migrations, EPC Group says it inventories users, groups, Shared Drives and Google Vault archives, maps permissions to SharePoint, rebuilds Apps Script automations in Power Automate and runs coexistence for two to four weeks before DNS cutover. - Microsoft’s own Google migration guidance does not currently support Office 365 US Government, GCC High or DoD, making a different route necessary for regulated buyers. - For hybrid organizations, EPC Group says it cleans and synchronizes identity first, then moves mailboxes, SharePoint farms and file servers, and retires on-premises servers only when nothing depends on them. - For consolidations, EPC Group says one written target-tenant decision, collision checks, wave sequencing, coexistence design and one evidence file per wave are required. - The firm said Microsoft’s native cross-tenant migration covers mailboxes, OneDrive and SharePoint, but leaves many project tasks to the customer or partner. - Microsoft’s cross-tenant mailbox feature does not migrate Microsoft 365 Groups, and Microsoft advises no more than 2,000 mailboxes per batch. - Microsoft’s cross-tenant OneDrive migration is a one-time move and does not allow incremental or delta passes. - Microsoft’s cross-tenant SharePoint migration does not include Teams content or channels, and workflows, apps, Power Apps and Power Automate flows must be recreated in the target tenant. - Microsoft says these migrations are not subject to service-level agreements. - Microsoft’s FastTrack cross-tenant service moves Exchange Online, SharePoint and OneDrive data but does not support Teams, Microsoft 365 Groups, Planner, Power Apps, device management or client configuration. - Microsoft 365 Government includes GCC, GCC High and DoD, with GCC serving government bodies and contractors handling US government data and GCC High serving defense contractors handling controlled unclassified information or ITAR-regulated data. - Microsoft says cross-tenant OneDrive migration is not supported for the Government Cloud, including GCC, GCC High and DoD. - EPC Group says it pairs GCC High projects with a CMMC Level 2 gap assessment.

Between the lines: - The press release is as much a productized methodology pitch as a milestone announcement. - EPC Group is arguing that migration success depends less on raw transfer tools than on planning, coexistence and rollback discipline. - The company is also signaling that government, defense and regulated customers need specialized routing because Microsoft’s standard tools leave gaps. - That emphasis lines up with the firm’s claim that most failures are decided before cutover, not during it.

What's next: - EPC Group says future work follows five phases: Diligence, Plan, Build, Cutover and Stabilize. - The firm says each engagement is led by a named senior architect and scoped after a one-hour call. - EPC Group says it uses a five-gate Day One model for deal migrations. - The company says its work continues in regulated environments including HIPAA, SOC 2, FINRA, FedRAMP, CMMC and GxP. - EPC Group also says it publishes anonymized case studies, a cutover and rollback checklist, and its broader migration guide for buyers evaluating vendors.

The bottom line: - EPC Group is betting that buyers will pay for migration execution, not just migration software, especially when deals, government clouds and coexistence risk are on the line.