Migrating from Google Workspace to Microsoft 365 is one of the more consequential infrastructure decisions an IT team can make. It’s not a software swap. It’s a full transition of how your organization communicates, stores files, manages identity, and enforces security across every user, on a deadline.
We’ve run this migration for organizations across verticals, including a recent engagement with a county government in Texas that moved approximately 120 user mailboxes and all Google Drive data to Microsoft 365. What follows is an honest account of what a migration like this actually involves, the common failure points, and how a structured approach is the difference between a clean cutover and a prolonged incident.
If your organization is evaluating this move, this guide covers the full picture: not just the steps, but the decisions that shape the outcome.
Why Organizations Are Leaving Google Workspace for Microsoft 365
The decision to migrate usually isn’t about features. Most organizations moving to Microsoft 365 are driven by three things: security posture, ecosystem consolidation, and long-term platform strategy.
Google Workspace has strong fundamentals. But when organizations need enterprise-grade identity management (Entra ID, Conditional Access), unified endpoint management (Intune), advanced compliance tools (Microsoft Purview), and an AI platform built into their productivity suite (Microsoft Copilot), Microsoft 365 wins on breadth. For organizations already running Azure, Dynamics, or Intune, adding M365 also eliminates the friction of managing a parallel Google environment.
There’s also the licensing angle. Many organizations find they’re paying for both platforms at once: full Google Workspace licenses and partial Microsoft 365 licenses for specific workloads. Consolidating onto M365 through a Cloud Solution Provider often reduces total spend while expanding capability.
For a closer look at how the two platforms differ in security, compliance, and AI, see our Microsoft 365 vs. Google Workspace comparison.
What Actually Moves: The Workload Map
Before planning a single migration batch, you need a clear picture of what moves and where it lands. Here’s the standard mapping:
| Google Workspace | Microsoft 365 |
|---|---|
| Gmail | Exchange Online |
| Google Drive (personal) | OneDrive for Business |
| Google Shared Drives | SharePoint Online |
| Google Calendar | Outlook Calendar |
| Google Contacts | Exchange Online Contacts |
| Google Chat / Meet | Microsoft Teams |
| Google Groups | Microsoft 365 Groups |
| Google Vault | Microsoft Purview Compliance |
Each workload has its own complexity and its own migration tooling. Gmail to Exchange is well-understood and highly automatable. Google Shared Drives to SharePoint is more nuanced because folder structure, sharing permissions, and site architecture decisions need to be made before migration begins, not during.
In the Texas county engagement, the scope covered Gmail migration for 120 users and full Google Drive migration to OneDrive. Shared Drives were explicitly out of scope, which is a standard scoping decision for mid-sized organizations that want to phase out complexity.
The Three Phases of a Google Workspace to M365 Migration
Every migration TrustedTech runs follows the same phased structure. The phases aren’t arbitrary: each one gates the next, and skipping steps in the planning phase is where most migrations fail.
Phase 1: Assess and Plan
This is the work most organizations underestimate. A proper assessment covers:
Inventory and scoping. Document every user account (active and inactive), mailbox sizes, Google Drive data volumes, folder structures, and sharing configurations. For the Texas county, this produced a complete object report with relative sizes before a single byte moved.
Risk identification. What mail flow rules exist in Google Workspace and need to be recreated in Exchange Online? Are there third-party email gateways that route inbound mail and affect DNS changes? Are there inactive mailboxes that need to be archived rather than migrated?
Cutover planning. Determine the cutover date, who controls DNS (often a shared responsibility between IT and a registrar or network team, and it matters), and the communication plan for end users. In the Texas county engagement, TrustedTech confirmed no third-party email gateways were in the path and that the client would retain DNS management, including SPF, DMARC, and DKIM updates.
User communication. End-user disruption is one of the most underestimated risks in any migration. Users logging into Outlook for the first time after years of Gmail need to know it’s coming, when it’s happening, and where to turn if something doesn’t work.
Phase 2: Design and Migrate
With planning complete, execution follows a pre-stage and cutover model:
Set up migration connections. This means creating an application registration in Google Workspace that grants the migration tool impersonation or delegated mailbox access. On the Microsoft side, Graph API permissions are configured so the migration tool can write to Exchange Online mailboxes and OneDrive.
Pre-migrate data. Before the cutover date, TrustedTech runs an initial pass that syncs all existing Gmail data into Exchange Online. Users keep working in Google Workspace while this happens with no disruption. For a 120-user organization, this pre-migration pass handles the bulk of the data volume.
Execute cutover. On the agreed cutover date, DNS MX records are updated to route new mail to Exchange Online. A final delta pass runs to capture any mail received after the pre-migration is completed. Users are then cut over to Outlook or Outlook on the web.
For Google Drive to OneDrive, the same pre-stage model applies: files sync before cutover, a final pass reconciles changes, and users move to OneDrive once the migration is complete.
Permission and UPN matching. One of the most operationally critical steps is matching Google Workspace user identities to Microsoft 365 UPNs. A mismatch sends files to the wrong OneDrive or creates orphaned data. TrustedTech builds a mapping table during the assessment phase and validates it before migration begins.
Phase 3: Validate and Optimize
Migration completion doesn’t mean migration success. Validation covers:
Mail flow confirmation. Verify that new inbound mail routes to Exchange Online rather than bouncing or going to Google. Confirm outbound mail sends correctly from Outlook.
Data integrity checks. Checksum comparison of source and target files for the Google Drive to OneDrive migration. Verify total file counts and sizes match. Review error logs for any items that failed.
Permission reconciliation. Confirm that OneDrive access permissions and security settings match the configuration. Remove all impersonation permissions and elevated migration service accounts.
Post-migration cleanup. Once validated, migration batches are deleted, Google Workspace sync is disabled, and temporary credentials are revoked.
The Tools Decision: Microsoft Native vs. Third-Party
One of the first questions clients ask is whether to use Microsoft’s built-in migration tools or a third-party platform. The honest answer depends on your environment.
Microsoft’s native tools (Exchange Admin Center, Migration Manager) are free, well-documented, and sufficient for straightforward Gmail and Google Drive migrations. The tradeoff: they require more PowerShell proficiency, offer less visibility into migration status, and have real limitations around large message sizes and certain calendar items. Microsoft’s own documentation notes that shared calendars and event colors won’t migrate, and that room bookings are excluded entirely.
Third-party tools (BitTitan MigrationWiz, ShareGate, Cloudiway) offer better delta sync, cleaner UPN mapping interfaces, richer reporting, and more automation for complex environments. They add tooling cost: roughly $15 per user for standard migrations, plus around $50 per Shared Drive if Shared Drives are in scope. For the Texas county engagement, TrustedTech’s tooling came to $1,800 for 120 users.
For most organizations migrating more than 50 users, the operational efficiency of third-party tooling justifies the cost. For smaller, simpler migrations, Microsoft’s native tools get the job done.
What Can Go Wrong (And How to Prevent It)
Every migration carries risk. Here are the failure modes we’ve seen most consistently, and how a structured approach addresses them.
Mail flow interruption. If DNS changes happen before the final delta migration completes, mail can be lost or delivered to the wrong system. Run a thorough DNS discovery before cutover, stage the changes precisely, and have a rollback plan ready.
Missing data. Users or objects left out of the original inventory don’t get migrated. Generate a complete object report in the assessment phase and have the client sign off on it before migration starts.
Credential and permissions errors. The migration tool loses access mid-run because a service account credential expires or impersonation permissions are revoked. Use just-in-time access where possible, validate credentials before large migration batches, and monitor for auth errors in real time.
MRM policy conflicts. Microsoft’s documentation explicitly flags this: any messaging records management or archival policy active in the source environment can cause the migration tool to flag items as “missing” when they’ve actually been deleted or archived by policy. Disable all MRM and archival policies before migration begins.
Scope creep. What starts as email-only grows to include Shared Drives, Google Sites, and Google Groups. Define scope explicitly in the statement of work, price change requests transparently, and build a formal change order process before the engagement starts.
What a Migration Engagement Looks Like End-to-End
For context, here’s the structure of the Texas county engagement:
Scope: 120 user mailboxes (Gmail to Exchange Online), Google Drive to OneDrive, mail flow and policy recreation, data integrity validation. Shared Drives and Azure resources were explicitly out of scope.
Team: A TrustedTech Delivery Manager overseeing the engagement, a Project Manager coordinating fieldwork and communications, and Migration Engineers handling technical execution.
Milestones and invoicing: Four equal milestone payments tied to contract execution, kickoff and planning completion, mid-project checkpoint, and final project completion. This structure keeps both parties accountable to progress, not just elapsed time.
Cost: $11,000 in professional services, $1,800 in tooling, for a total of $12,800 for a 120-user migration. That’s roughly $107 per user all-in for a structured, managed engagement with pre-migration validation, delta sync, and post-migration QA.
Assumptions that matter: The county retained responsibility for DNS management (SPF, DMARC, DKIM), provided global admin access to both environments, and agreed to validate the migrated object list as part of QA. These aren’t fine print. They’re real dependencies. A migration slows down or fails when client-side responsibilities aren’t met on schedule.
Frequently Asked Questions
Q. How long does a Google Workspace to Microsoft 365 migration take?A. It depends on data volume and user count. A 120-user migration with full mailbox and Drive data typically runs 3 to 6 weeks from kickoff to final cutover, including pre-migration, validation, and DNS changes. Larger environments or those with complex Shared Drive structures will take longer.
Q. Do users experience downtime during the migration?A. A properly staged migration keeps downtime to a brief cutover window. The pre-migration pass runs while users continue working in Google Workspace. The actual cutover, which covers DNS updates and the final delta pass, typically results in less than one hour of disruption when coordinated correctly.
Q. What data doesn’t migrate cleanly from Google Workspace to Microsoft 365?A. Microsoft’s native migration tools don’t migrate shared calendars, room bookings, or event colors. Google Chat and Meet data require separate tooling. Native Google file formats (Docs, Sheets, Slides) can be converted to Office formats during migration or preserved as links; the right choice depends on your organization’s preference.
Q. Who manages DNS changes during the migration?A. DNS changes are typically the client’s responsibility, executed in coordination with TrustedTech’s cutover plan. This includes updating MX records, SPF, DKIM, and DMARC. TrustedTech provides timing and configuration guidance; the client or their DNS registrar executes.
Q. What Microsoft 365 licenses do we need before migration starts?A. You’ll need active Microsoft 365 licenses for all migrating users before migration begins. Exchange Online mailboxes and OneDrive storage need to be provisioned as migration targets. The right plan depends on your security, compliance, and productivity requirements. TrustedTech can help you select the right licensing tier before the engagement starts.
Q. Can TrustedTech handle the migration if we already purchased Microsoft 365 licenses elsewhere?A. Yes. TrustedTech can execute the migration regardless of where your M365 licenses were purchased. If you’d like to consolidate licensing through TrustedTech as a CSP, we can evaluate whether a mid-cycle move makes financial sense for your renewal timeline.
Get Started with a Migration Readiness Assessment
A Google Workspace to Microsoft 365 migration is a structured engineering project, not a configuration wizard. The organizations that execute it cleanly invest in the assessment phase, define scope precisely, and work with a partner that has done this before.
TrustedTech’s migration team has run these engagements for government agencies, professional services firms, and enterprise organizations. We handle planning, execution, validation, and cleanup, and we structure our engagements so you’re paying for progress, not just time.
If you’re evaluating this move, start with a migration readiness assessment. We’ll inventory your environment, identify the risks specific to your configuration, and give you a clear scope and timeline before any work begins.
Talk to TrustedTech’s migration team to schedule your assessment.
