Our new CEO wants us to move from Google Workspace to Microsoft 365 by the end of the year. Most employees rely heavily on Gmail, Drive, Docs, Sheets, Forms, Google sign-in, SSO integrations, and various third-party services, while only a few regularly use Word or Excel. We also have less obvious dependencies such as copiers configured for scan-to-email, public Google Forms, Windows accounts using Google authentication, and many applications connected through "Sign in with Google."
There may be more than 20 vendors and an unknown number of employee-created integrations to review. Leadership seems to expect that the main migration could be completed in about a month, with some Google services remaining online temporarily. I'm considering hiring a specialist migration company and arranging training because I'm supporting more than 70 employees on my own.
For organizations that have completed this kind of migration, how difficult was it in practice? What hidden dependencies, data-conversion problems, licensing issues, or user-training challenges did you discover? I'd especially appreciate advice on planning, testing, migration tools, and setting realistic expectations for the timeline.
5 Answers
I would push back on the one-month expectation unless the environment is unusually small and simple. A realistic project usually includes discovery, licensing and storage design, pilot migrations, application remediation, user communication, training, staged cutovers, and post-migration cleanup. Even organizations with extensive testing still find undocumented systems because employees create workflows without telling IT. Keeping a few Google services temporarily may be possible, but it adds identity, security, and administration complexity.
Treat this as a discovery and change-management project rather than a simple mail migration. Gmail can often be moved fairly smoothly, but Google Docs and Sheets may need conversion and testing because formatting, formulas, scripts, links, and inter-file references can break. Google Forms, Google Sites, Meet content, shared-drive permissions, and complex folder structures generally need separate planning or rebuilding. Also check mailbox sizes, SharePoint and OneDrive capacity, path-length limits, Chrome profile synchronization, and how users will be trained on the new applications.
That user-training piece is significant when one administrator supports more than 70 people. Budget for structured training and a support period after cutover instead of treating the project as finished when the data transfer ends.
Before approving the project, build a complete inventory: domains, users, aliases, groups, shared drives, mailbox sizes, documents, forms, scripts, external sharing, SSO apps, OAuth connections, vendors, devices, and data-retention requirements. Pay particular attention to storage limits. Microsoft’s default SharePoint and OneDrive allocations may not match the amount of data currently in Google, and additional storage can be expensive. The migration is possible, but the CEO should understand that doing it properly requires budget, specialist help, and a staged schedule rather than just copying mail and files.
The biggest surprises are usually SSO and third-party applications, not the mailbox move itself. Inventory every OAuth connection, “Sign in with Google” account, vendor integration, scanner, copier, mobile app, and automation before changing anything. User-level security pages can reveal some linked applications, and tools such as GAM can help inventory OAuth tokens. Don’t assume that creating a Microsoft login with the same email address will automatically preserve data or account ownership in an external service.
Use a migration platform such as BitTitan MigrationWiz or a comparable service, and run a pilot before committing to the full cutover. Set up and validate the required Google API permissions first, perform trial migrations, test representative mailboxes and shared data, and document the results. Microsoft FastTrack may also be worth evaluating, especially if your licensing qualifies. For security, review Entra ID licensing carefully so you have the conditional-access and MFA controls you actually need; don’t choose licenses based only on the migration tool.
Conditional Access is available with the appropriate Entra ID licensing, so verify the exact features and license requirements rather than assuming the highest tier is mandatory. The important part is having a tested identity, MFA, and device-access plan before moving users.
A six-month planning horizon is much more believable for a deeply integrated environment. An MSP or migration specialist can reduce the internal workload, but outsourcing does not eliminate the need for testing, decisions, training, or time.