How to leave Microsoft 365: a step-by-step plan

To leave Microsoft 365, list what you use, decide what stays, move one team first, then move mail and files and switch your domain over before the subscription ends. The date that drives the whole plan is your licence renewal, because under Microsoft's current commerce terms a subscription can only be cancelled in the first seven days of a term.

The steps below assume you are moving to open-source systems in your company's name. The Microsoft side of the plan applies whatever you move to.

Step 1: List what you use

Start with an audit. It is quicker than finding things out halfway through.

• Licences: which plans, how many seats, monthly or annual term, the renewal date, and whether you buy direct from Microsoft or through a partner.
• Mail: every mailbox, including shared mailboxes, distribution lists, aliases and forwarding rules.
• Files: SharePoint sites, files kept in Teams channels, and each person's OneDrive.
• Other services: Forms, Power Automate flows, Bookings and anything else people rely on.
• Sign-in: third-party apps that people sign into with their Microsoft account, such as accounts packages and CRMs.
• Devices: every PC, laptop and phone, which Windows version it runs, and whether it can take Windows 11.
• DNS: who controls your domain and where its DNS is hosted.

The sign-in list matters more than it looks. If an app uses "Sign in with Microsoft", people lose access to it when their Microsoft account goes, so each one has to move to the new sign-in, or to its own login, first.

Step 2: Decide what stays

Not everything has to go. You might keep Teams for client meetings, keep Exchange Online for a while, or keep one Windows machine for software that only runs on Windows. Whatever stays still needs licences, so decide before the renewal date, not after. The guide to Microsoft 365 alternatives goes through each piece.

Step 3: Plan around your renewal dates

Microsoft 365 subscriptions run in terms, which can be monthly, annual or three years (Microsoft Learn: new commerce). Find the end date of each subscription in the Microsoft 365 admin center, or ask the partner who sells them to you. Then plan backwards from it.

• Cancelling early. Under Microsoft's current commerce terms, a subscription can be cancelled for a prorated refund only within seven days of it starting or renewing (Microsoft Learn: cancellation policy). Some older accounts bought direct from Microsoft work differently, so check which kind of billing account you have.
• After the seven days. You turn off recurring billing, and you keep access until the end of the term. An annual subscription paid monthly is still charged each month until the term ends (Microsoft Learn: cancel your subscription).
• Seats you still need. If some people will stay on Microsoft 365 for a while, a partner can schedule changes, such as fewer seats, to take effect at the end of the term.

Leave a margin. Aim to finish the move, and check it, a few weeks before the end date.

Step 4: Build the new setup and run a pilot

Set up the new services first: sign-in, mail, files and chat on servers in your company's name. Then move one team. Pick one whose work is mostly in a browser, so the pilot tests the new systems rather than a Windows-only app.

The pilot team can start with their desktops, files and chat, with their mail following at the main switch-over. They do their real work on the new setup while everyone else carries on as before. Fix what they find before anyone else moves. Desktops then move team by team, with each PC rebuilt on Ubuntu or replaced if it isn't worth keeping. The guide to Linux desktops for business covers the desks.

Step 5: Move the files

Copy SharePoint libraries, Teams files and OneDrive folders to Nextcloud, keeping the folder structure and giving the same people the same access. Do a bulk copy first while people are still working, then a final copy of anything that changed at the switch-over. On the day, make the old libraries read-only so nobody saves to the wrong place.

A plain copy brings across the current version of each file, not its version history. Decide early whether you need that history, and if so, how it will be kept.

Step 6: Move the mail

Mailboxes, calendars and contacts are copied to the new mail server the same way: a bulk copy ahead of time, then a final pass on the day. Shared mailboxes, distribution lists and aliases are set up on the new server before the switch, so nothing bounces. On the day, people's computers and phones are pointed at the new server.

Step 7: Switch the DNS

Your domain belongs to you, so your email addresses stay the same. The switch happens in DNS:

1. Lower the time to live (TTL) on the records you will change a day or two before, so the change takes effect quickly.
2. Point the MX record at the new mail server.
3. Update SPF, add DKIM signing for the new server and keep a DMARC policy in place. The NCSC explains all three in its email security and anti-spoofing guidance.
4. Remove records that point at Microsoft services you no longer use, such as Autodiscover.
5. If your nameservers are hosted by Microsoft 365, move them to a DNS provider on an account in your company's name.

If you are leaving completely, Microsoft requires you to remove your custom domain from Microsoft 365 before you cancel. That means moving every user, shared mailbox, group and admin account off the domain first. Microsoft says removal can take from five minutes to a day, depending on how many places the domain is used (Microsoft Learn: remove a domain). If you are keeping some Microsoft services, the domain may need to stay in Microsoft 365, and the DNS changes are planned around what stays.

Step 8: Keep access to old data

When a subscription reaches its end date, Microsoft describes these stages for most subscriptions (Microsoft Learn: what happens when your subscription ends):

The stages depend on how you bought the subscription. Microsoft notes that since 9 February 2026 the Expired stage no longer applies to licence-based subscriptions bought directly on a Microsoft Customer Agreement. It also says that data left behind after you cancel is deleted no later than 180 days after cancellation, and that if a subscription is deleted outright, SharePoint and OneDrive content goes immediately. Buying a new subscription later doesn't bring deleted data back.

Treat these stages as a safety margin, not as time to finish the move. Before the end date:

• export every mailbox and file library you need to keep, including those of people who have left;
• keep the archive on storage your company owns, in formats that open without Microsoft software;
• check how long you have to keep records: a limited company must keep company and accounting records for 6 years from the end of the last financial year they relate to, and sometimes longer (GOV.UK: company and accounting records);
• check for anything under a legal hold or retention policy, and agree how it will be kept.

Step 9: Decommission

Once everyone has moved and the archive has been checked:

• switch any remaining "Sign in with Microsoft" apps to the new sign-in;
• remove the domain from Microsoft 365;
• turn off recurring billing on each subscription you no longer need;
• remove old Windows PCs from Intune, and wipe or rebuild them before they are reused or recycled;
• close the admin accounts you no longer need, and record what was closed and when.

From then on, the domain, servers, hosting accounts and admin passwords are all in your company's name. Self-custody explains how that works day to day.

Every step is easier with the plan written down before anything moves. Book a planning call and we'll go through your licences, renewal dates and what has to stay, then set out the order.

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