Google Workspace to Microsoft 365: the SMB migration checklist.
A Google Workspace to Microsoft 365 migration moves a company’s email, files, calendars and user identities from Google’s cloud to Microsoft’s. Done in the right order it’s a quiet weekend; done wrong it’s a fortnight of bounced mail and broken share links. Here’s the order we use.
- Pre-sync all mail and files into Microsoft 365 before you touch MX records — never cut over cold.
- Identity and the domain switch are all-or-nothing; data can move in waves, the domain cannot.
- The thing that bites SMBs isn’t mail — it’s Google share links, shared Drives and third-party app sign-ins breaking.
- Budget two to four weeks for 10–50 users, with the cutover itself on a Friday evening.
Before you start: is M365 even the right move?
For most UK SMBs the answer is yes — not because Microsoft 365 is better software, but because of where the rest of your stack lives. If you run Windows laptops, need Cyber Essentials, want device management through Intune, or your accountant, lawyer and clients all send Office files, M365 reduces friction across the board. If your team is all-Mac, lives in Google Docs, and has no compliance pressure, the case is weaker. Decide on the destination before you plan the route.
This guide assumes you’ve made the call and want the move to be boring. That’s the goal: boring.
The migration in five phases
Every clean migration we run follows the same shape. The phases matter more than the tooling.
Phase 1 — Prepare the Microsoft 365 tenant (week 1)
- Buy the right licences. Business Standard for most; Business Premium if you want security and device management bundled (you do — it includes Intune, Entra P1 and Defender).
- Verify your domain in Microsoft 365 without changing MX yet. You’re proving ownership, not redirecting mail.
- Create every user, group and shared mailbox. Match display names and aliases exactly so replies to old addresses still land.
- Set up Entra ID: enforce MFA, build conditional access, and decide your password policy now, not after.
Phase 2 — Pre-sync the data (still on Google)
This is the phase people skip and regret. While everyone is still working in Google, a migration tool copies historical mail, calendars and contacts into the new M365 mailboxes in the background.
- Mail, calendars, contacts sync mailbox by mailbox. Run an initial full pass, then top-up deltas closer to cutover.
- My Drive → OneDrive, per user.
- Shared Drives → SharePoint libraries or Teams sites. Map these deliberately — this is where structure gets decided for the next five years.
Phase 3 — Cut over the domain (Friday evening)
The actual switch is the smallest part. You change the domain’s MX record to point at Microsoft 365, update SPF, and add DKIM and DMARC records. From that moment, new mail flows to M365. Because you pre-synced, history is already there. Keep the Google tenant live for a couple of weeks as a safety net.
Phase 4 — Reconnect the humans (Monday morning)
Outlook profiles, phones, and any line-of-business apps that signed in with Google all need re-pointing. Have a one-page “Monday morning” guide ready and someone on hand for the first two hours. This is where a smooth migration is won or lost in the team’s perception.
Phase 5 — Decommission and harden (week 3–4)
Once you’ve confirmed nothing’s missing, cancel Google licences, finalise backup of the new tenant, and lock down sharing defaults. A migration isn’t finished until the old system is off and the new one is properly administered.
The migration tool is 20% of the job. The other 80% is identity, share links, and the Monday morning a human notices their printer scan-to-email stopped working.
The five things that actually break
In ascending order of how much they ruin someone’s week:
- Google share links. Every
drive.google.comlink in old emails, signatures and documents dies. Re-share the files that matter; accept that ancient links won’t resolve. - Shared mailboxes and groups. Google’s collaborative inboxes don’t map 1:1. Decide which become M365 shared mailboxes and which become distribution lists.
- Third-party sign-ins. Anything your team logged into “with Google” now needs a Microsoft identity or a local account.
- Calendar invites in flight. Recurring meetings created in Google can detach. Re-issue the important standing meetings.
- Scan-to-email and app passwords. Printers and old devices using SMTP need the new server settings and, often, an app password under the new MFA policy.
What it costs and how long it takes
For a 10–50 user UK business, expect two to four weeks of elapsed time with only a few hours of actual disruption. The licence cost steps up versus Workspace, but for most SMBs that’s offset by dropping separate security, backup and MDM tools that M365 Business Premium folds in. The real cost is doing it twice because the first attempt skipped the pre-sync.
Questions we get asked.
How long does a Workspace to Microsoft 365 migration take?
For a typical UK SMB of 10–50 users, plan two to four weeks end to end: about a week of prep and tenant setup, a few days of pre-sync while everyone still uses Google, a weekend cutover, then a week of cleanup. Mailbox volume and the number of Shared Drives are what stretch it.
Will we lose any email during the migration?
Not if it’s done with overlapping delivery. You pre-sync all historical mail into M365 before changing MX records, then keep both systems live during cutover so nothing bounces. Done properly, no message is lost.
What happens to our Google Drive files?
My Drive maps to OneDrive; Shared Drives map to SharePoint or Teams. Google-format files convert to Office formats. The catch is sharing links break and need re-issuing — the part most teams underestimate.
Do we have to migrate everyone at once?
Data can move in waves, but the domain cutover is all-or-nothing because MX points to one provider at a time. Most SMBs sync in waves, then cut the whole domain over in one weekend.
Let’s scope your
migration.
30 minutes. We’ll map your current Workspace setup, flag what’ll break, and give you a realistic timeline and price — whether you run it yourself or hand it to us.