Microsoft 365 tenant to tenant migration
Merge two companies’ email and files by the deal date, with every person checked on both sides.
The agreed users, mail and files land in the receiving tenant. Sign-in and mail work on the new path, and every user is checked across both sides.
- What you get
- The agreed users, mail and files in the receiving tenant, with migration checks and a handover record.
- How it starts
- A free scope call. The price is fixed in writing before anyone is given access.
- When it is done
- Every in-scope user is accounted for and agreed services are tested; anything left behind has an owner and a date.
Illustrative sample · constructed example
Follow one person across both tenants.
Illustrative merger · project coordinator
Selected check
Is the domain transition agreed on both sides?
Illustrative merger · project coordinator
| Record | Evidence or responsibility | Sample review |
|---|---|---|
| Domain and identity | Both owners agree the domain release and sign-in timing. | Transition not approved |
| Mailbox | Test the person’s sign-in and agreed mailbox in the target. | Target account exists |
| Project Team | Check membership and the user’s actual task separately. | Access review pending |
| OneDrive | Verify its agreed migration path and acceptance record. | Separate workload check |
Accept each workload on its own evidence; tenant access alone does not complete the move.
- Evidence
- Target account exists; domain release and sign-in timing are not approved.
- Decision
- Hold the affected wave
- Next action
- Both tenant owners agree the transition and user communication.
Illustrative sample. Workloads have different migration paths; a mailbox result is not a Teams or OneDrive result.
Open the complete illustrative document to inspect its fields and print a copy.
Open the sample documentWhy now
The work starts here.
A sale, a purchase or a company split means one Microsoft 365 tenant has to move into another. The date is usually agreed before IT is asked.
Scope at a glance
- Clashes found before the first user moves
- Checked user by user before sign-off
- You own staff support on both sides
If nobody acts
What waiting costs
A domain can only be attached to one tenant at a time, so the moment it moves, sign-in and mail for everyone using it moves with it, whether or not the rest of the work is ready.
Where the two sides cannot see each other’s calendars or message each other during the move, the business runs as two companies for that period, and the people affected are usually the ones closing the deal.
Security rules that do not come across leave accounts on the receiving side protected differently from the way they were the day before, and nobody notices until something uses the gap.
A deal date is fixed by people who are not in IT, and a move that has to be rebuilt from scratch when a clash is found is only as complete as the days left before that date.
Check your own environment
Sounds like you?
- A deal has a date on it and IT was told about it late
- The same person has an account on both sides
- One domain name is needed by both businesses
- People on the two sides cannot see each other’s calendars or message each other
Save yourself the call
Not for you if
- The two businesses are staying on separate tenants
- Only mail is moving, and it is coming from a host rather than another tenant
- Nobody has agreed which side is receiving, which has to be settled first
The work
What is different when we hand over
Everything in scope is counted on both sides before anything moves, and every user gets a named destination.
The clashes are found first: shared domains, duplicate accounts, and security rules that differ between the two tenants.
How much the two sides can see of each other during the move is decided and set up in advance, rather than discovered on the first morning.
The move runs in dated groups, and each group is checked before the next one starts.
The receiving tenant is checked against the source user by user, and every gap is closed or given an owner.
Acceptance
Checks before handover
Every user on the agreed list can sign in on the receiving tenant
Mail and files for those users have arrived and are tested
Every user is counted across both tenants, and anything deliberately left behind is written down with an owner and a date
A fair question
Both sides are Microsoft 365. Should this not be straightforward?
Same platform, but the parts that clash are the same parts either way. A domain can only live in one tenant, so the moment it moves, sign-in and mail move with it. The same person may exist on both sides. And the two businesses almost never wrote their security rules to agree with each other. Those are the three things that decide the schedule.
Price and calendar
Scope, price and project calendar
Engagement price
Price fixed after a short scope call.
The price is agreed in writing before any work starts and before anyone is given access. The call itself costs nothing. What moves the number:
What determines the scope
- How many users are moving
- Which parts of Microsoft 365 are in scope: mail, files, Teams, devices
- Whether the two tenants have to work side by side during the move, and for how long
- Whether devices have to be re-enrolled on the receiving side
- How many domains move, and whether any are shared between the two businesses
Delivery calendar
The calendar is set once the data, the dependencies and the cutover requirements have been checked, then fixed in writing before the move begins.
How engagements workScope & responsibilities
What is and is not included
The exclusions, what we need from you, how change is staged and reversed, and what is handed over at the end.
Exclusions
- Licenses needed to run the move, on either side
- Application rebuilds or integrations on the receiving side
- HR, payroll or finance system moves
- Help desk and staff support
What we need from you
- Confirm the list of users, domains and data that moves
- Approve the switch window and the period the two sides run side by side
- Give administrator access to both tenants
- Tell staff on both sides what is happening and support them through it
Change and rollback method
- Users move in dated groups, and a group is not started until the one before it checks out.
- The conditions that stop the move are agreed before the first user moves, and they name conditions rather than intentions.
- The domain move is scheduled as its own step, with its timers shortened in advance, because it takes sign-in and mail for everyone on it at the same moment.
What you keep at handover
- A System guide: the configuration as delivered, the checks that were run and the unresolved list
- The counted list of users, mail and files that moved
- The list of clashes found and how each was settled
- The dated schedule, as it actually ran
- The agreed conditions for stopping
- The check sheet proving source and destination match
Access, acceptance and support arrangements
How you know the work is good
Judge it by what you can inspect.
The method is written down, the sample records open and the demo can be broken on purpose. Read it the way your technical owner would.
- 01How a project runs
A first conversation, free. An agreed scope with a named technical lead in the proposal. The price fixed in writing before we are given access. Checks before handover.
How we work- 02What is checked
Release checks, access test matrices and ownership maps. Constructed inspection records on the service pages show the standard before you buy.
See sample deliverables- 03What you keep
A System guide: what was agreed, what changed, what was tested and what remains open. With it, the scripts and check results behind the work.
Next step
Start with a free scope call.
Tell us what needs to change, what must keep working and the deadline. The call is free, and the price is fixed in writing before anyone is given access.
Price the tenant moveOr write to [email protected]