Microsoft 365 migration cost is the number every UK business wants before it commits, and it is the number almost nobody quotes honestly. Ask three providers and you will get three figures that differ by a factor of four, because each one has quietly assumed a different scope, a different starting point and a different definition of “done”. None of them is necessarily lying. They are answering different questions.
This guide unpicks that. It sets out what a Microsoft 365 migration cost actually contains, what UK businesses of various sizes really pay in 2026, how long the work takes week by week, and which decisions genuinely move the number. The figures are the ones a competent provider would recognise, not the optimistic ones on a landing page.
Two things are worth saying before the numbers. First, the licence bill and the project bill are separate animals, and confusing them is the single most common budgeting error. Second, the cheapest Microsoft 365 migration cost on the table is usually the most expensive over three years, because the corners cut in week two get paid for in month fourteen.
If you are also moving servers and line-of-business applications, that is a different project with a different budget — see our guide to cloud migration cost in the UK for that side of the estate. This article is about the productivity platform: mailboxes, files, identity, Teams and devices.
Table of contents
- What a Microsoft 365 migration cost actually covers
- Microsoft 365 migration cost by business size in the UK
- The hidden extras that inflate a Microsoft 365 migration cost
- Licensing: the part of the bill that never stops
- A realistic Microsoft 365 migration timeline, week by week
- What actually drives the Microsoft 365 migration timeline
- How your starting point changes the Microsoft 365 migration cost
- Cutover weekend and the costs that surface afterwards
- How to reduce a Microsoft 365 migration cost without cutting corners
- Questions to ask before you sign
- Frequently asked questions about Microsoft 365 migration cost
- Turning the estimate into a decision
What a Microsoft 365 migration cost actually covers
Before comparing quotes, you need a shared vocabulary for what is being priced. A Microsoft 365 migration cost is made of five distinct components, and most quotes include some and silently omit others.
Discovery and assessment
Somebody has to look at what you currently have: mailbox count and sizes, public folders, shared mailboxes, distribution groups, the file server, the permissions on it, which applications send email, and how identity works today. This is normally one to three days of work, and it is the part providers most often skip to look cheap. It is also the smallest line in any Microsoft 365 migration cost and the one that protects every other line. Every unmapped item found in week five costs several times what it would have cost to find in week one.
Tenant build and identity foundation
Domain verification, DNS, directory synchronisation or cloud-only identity, multi-factor authentication, Conditional Access, naming conventions and administrative roles. This is a one-off build, and it is the part of the Microsoft 365 migration cost that determines whether the tenant is manageable in three years or a mess you pay somebody to unpick.
Data movement
Mailboxes, archives, OneDrive content, file shares into SharePoint, and Teams structure. Data movement is the visible part of the project and typically only a third of the effort, which is why a Microsoft 365 migration cost built purely on gigabytes moved is always wrong. Tooling licences for a third-party migration product sit here too.
Cutover and hypercare
The switch itself — MX record changes, Outlook profile re-creation, mobile devices, printers that scan to email — followed by one to two weeks of elevated support while people hit the things testing never finds.
Change, training and adoption
The line item cut first and regretted most. A tenant nobody knows how to use produces a support queue that quietly outlives the project by a year, and that queue never appears in the Microsoft 365 migration cost anybody quoted you.
Microsoft 365 migration cost by business size in the UK
Real numbers help more than formulas. These are professional-services ranges for a UK provider in 2026, excluding licences and excluding VAT, for a business coming from on-premises Exchange or Google Workspace.
Under ten users
A straightforward migration for a micro business lands between £750 and £2,500. At this size the work is dominated by fixed tasks — DNS, tenant setup, testing — rather than per-user effort, so the Microsoft 365 migration cost per head looks high and the total looks small. Most of these are done over a single weekend.
Ten to fifty users
Expect £2,500 to £9,000. This is the most common band for UK SMEs and the one where quotes vary most wildly, because it is the band where a provider can either do it properly or do it fast. A realistic per-user Microsoft 365 migration cost here is £90 to £180 once discovery and identity work are included.
Fifty to one hundred and fifty users
Expect £9,000 to £28,000. At this size you almost certainly have a file server with inherited permissions nobody understands, at least one legacy application relaying email, and a hybrid identity requirement. The Microsoft 365 migration cost is driven far more by those three things than by user count.
One hundred and fifty to three hundred users
Expect a Microsoft 365 migration cost of £28,000 to £70,000, usually delivered in waves rather than one weekend. Parallel running, staged mail routing and a proper pilot group become mandatory rather than optional, and project management becomes a visible line rather than an overhead absorbed by the engineer.
Why per-user pricing is a rough guide only
Per-user maths is useful for sanity-checking a quote and useless for producing one. A fifty-user professional services firm with clean data and cloud identity is a genuinely different project from a fifty-user manufacturer with a twenty-year-old file share, a scanner fleet and a bespoke ERP that sends invoices by SMTP.
Nearly every overspend traces back to the same small set of items. None of them is exotic. All of them are foreseeable.
File server permissions
The single biggest hidden cost. Years of nested groups, individual user permissions and folders shared “temporarily” produce a structure that cannot be lifted into SharePoint as-is. Someone has to decide what the permission model should be, which is a business decision that consumes management time as well as engineering hours.
Mailbox size and archives
Large mailboxes, enormous PST files under people’s desks, and shared mailboxes used as filing systems all slow data movement and add remediation. A twenty-gigabyte mailbox is not twenty times harder than a one-gigabyte mailbox, but a hundred PSTs discovered late absolutely will move your Microsoft 365 migration cost.
Applications that send email
Copiers, CRM systems, accounting packages, alarm panels and bespoke line-of-business tools all relay mail. Each one needs identifying, reconfiguring and testing. Finding them after cutover means finding them because an invoice run failed.
Third-party migration tooling
Above roughly thirty users, most providers use a commercial migration tool rather than native methods. Licences are typically charged per mailbox for a fixed window and are a legitimate, and modest, part of any Microsoft 365 migration cost — but they should be visible, not buried.
Devices, printers and the long tail
Older machines that will not run a current Outlook build, scanners that only speak unauthenticated SMTP, and the one machine in the workshop running an ancient operating system. These are cheap individually and expensive collectively, and they are the commonest reason a final invoice exceeds the Microsoft 365 migration cost that was quoted.
Overlap and dual running
For anything above a single weekend cutover you may be paying for both platforms at once. Two to eight weeks of overlap is normal, entirely predictable, and it belongs in the Microsoft 365 migration cost from the first draft of the budget.
Licensing: the part of the bill that never stops
Project fees are one-off. Licences are forever, and over three years they dwarf the migration itself.
Where list pricing sits in 2026
Annual-commitment list pricing sits broadly around £17 to £19 per user per month for Business Premium, £30 to £33 for E3, and £48 to £53 for E5, excluding VAT. Business Basic and Business Standard sit well below that for organisations that do not need the security and device management layers.
Why the licence decision outweighs the project fee
At fifty users over three years, the gap between Business Premium and E5 is tens of thousands of pounds — comfortably more than the entire Microsoft 365 migration cost for that business. Getting the licence mix right is therefore the higher-value decision, and it deserves more scrutiny than haggling over project days. Our Microsoft 365 licence comparison walks through the tiers in detail.
Mixed licensing is normal and underused
Not everybody needs the same licence. Frontline and shop-floor staff often need far less than knowledge workers, and licensing them identically is a recurring waste that no amount of project discipline recovers.
Do not buy the licences too early
Buying annual licences weeks before the migration starts pays for a service nobody is using yet. Align the subscription start date with the pilot, not with the contract signature.
Budget for the run-rate, not just the project
A Microsoft 365 migration cost that ignores the ongoing bill produces a nasty surprise at the first renewal. Build the recurring figure into your IT budget planning from the outset rather than treating it as a project overspend.
A realistic Microsoft 365 migration timeline, week by week
Timelines slip for predictable reasons. Here is what a well-run fifty-user project looks like when nothing goes badly wrong.
Week one: discovery and design
Inventory of mailboxes, files, applications and devices. Decisions on identity model, licence mix and the SharePoint structure. Output is a written plan, not a conversation.
Weeks two and three: tenant build and identity
Domains verified, DNS prepared with reduced time-to-live values, directory synchronisation configured, multi-factor authentication and Conditional Access policies built and tested against a pilot group.
Weeks three and four: pre-staging data
Bulk copy of mailbox and file data while the old platform stays live. This runs quietly in the background and is why a well-planned cutover weekend feels uneventful.
Week five: pilot group
Ten to fifteen users representing every department move fully. Every problem the wider business would have hit surfaces here, cheaply, with a working rollback.
Week six: cutover
Final delta sync, MX change, profile re-creation, mobile devices, printers and relays. Usually a Friday evening to Sunday afternoon window.
Weeks seven and eight: hypercare and closure
Elevated support, permission fixes, decommissioning of the old platform, and handover documentation. Closing the project without decommissioning is how businesses end up paying for both platforms indefinitely.
Where the six weeks becomes twelve
Almost always for non-technical reasons: unavailable decision-makers, unresolved file permissions, an application vendor who takes three weeks to answer, or a business that will not release users for a pilot. Delay of that kind raises the Microsoft 365 migration cost twice over, once in project management and once in extended dual running.
What actually drives the Microsoft 365 migration timeline
User count is a weak predictor. These five factors are strong ones.
Your source platform
Google Workspace to Microsoft 365 is generally cleaner than on-premises Exchange, because identity and mail are already cloud-native. A hybrid Exchange environment that must stay hybrid is the slowest of all. If you are still weighing the platforms, our Google Workspace versus Microsoft 365 comparison covers the ground.
Data volume and shape
Total gigabytes matter less than the number of objects. A million small files is a harder migration than a few very large ones, and permissions multiply that difficulty. Object count, not volume, is what a sensible Microsoft 365 migration cost is estimated against.
Regulatory and retention obligations
Legal hold, retention policies and sector rules add design time and testing, particularly in finance, healthcare and legal practices. They rarely add much engineering, but they add decisions.
Internal availability
The fastest projects are the ones where a named person on the client side can make decisions in a day. The slowest are the ones waiting on a committee.
Appetite for cleanup
Deciding to fix the file structure during the migration is often correct, but it converts a technical project into a business one and typically adds two to four weeks.
How your starting point changes the Microsoft 365 migration cost
The same fifty users can produce very different quotes depending entirely on where they are coming from.
From on-premises Exchange
The classic scenario, and the most variable. A single modern Exchange server with tidy data is straightforward. An older server, public folders and a hybrid requirement can double the Microsoft 365 migration cost through remediation alone.
From Google Workspace
Usually cheaper on the technical side and more expensive on the human side. The data moves predictably; the change management does not, because everybody’s daily habits change at once.
From IMAP, POP or a hosting provider
Mail moves easily, but there is often no directory at all, so identity has to be built from scratch. Shared file storage is frequently a consumer sync tool that nobody controls.
From an existing but neglected tenant
Increasingly common, and awkward to price. You are not migrating so much as remediating, and the honest first step is an audit. Our Microsoft 365 security audit checklist sets out what that review should cover before anybody quotes remediation work.
From a tenant your outgoing provider controls
If a partner holds the tenant, transferring administrative control is a commercial conversation as much as a technical one. Start it early — it is a common cause of delay and a recurring theme when businesses switch IT support providers.
Cutover weekend and the costs that surface afterwards
The migration is not finished when mail arrives in the new platform. Several real costs land in the fortnight after.
The support spike is real and short
Expect two to three times normal ticket volume for around ten working days. Providers price this either as included hypercare or as time and materials, and you should know which before you sign.
Permissions always need a second pass
However carefully SharePoint is designed, real usage exposes gaps within days. Budget a day or two of post-migration permission work as a certainty rather than a risk.
Backup is not included
Microsoft protects the platform; it does not keep a long-term backup of your data on your behalf. Third-party backup is a recurring cost that belongs in the business case from day one — our guide to Microsoft 365 backup explains what native retention does and does not do.
Decommissioning is a task, not an afterthought
Old servers, old licences, old backup jobs and old maintenance contracts all need cancelling. This is where a chunk of the Microsoft 365 migration cost is recovered, and it only happens if somebody owns it.
Training pays for itself quietly
A short, practical session on Teams and SharePoint conventions in week seven removes months of low-grade support tickets. It is the cheapest line item in the project and the first one cut.
How to reduce a Microsoft 365 migration cost without cutting corners
There are legitimate savings and false ones. These are the legitimate ones.
Do the cleanup before, not during
Archiving dead data, closing leavers’ accounts and deleting obsolete shares before the project starts reduces the volume you pay to move. A tidy onboarding and offboarding process prevents the accounts accumulating in the first place.
Accept a standard design
Bespoke tenant designs cost real money and rarely earn it. A provider’s standard, well-documented pattern is cheaper to build and far cheaper to support afterwards.
Move in waves only when you need to
Waves reduce risk and increase cost through repeated coordination and longer overlap. Below roughly eighty users a single well-rehearsed cutover is usually both cheaper and less disruptive.
Right-size licences at the start
Mixed licensing applied on day one avoids a costly true-up later. Reviewing tiers annually keeps the recurring Microsoft 365 migration cost from drifting upwards unnoticed.
Insist on a fixed price for a fixed scope
A fixed price with a written scope and a named change-control process protects both sides. Time and materials with a vague scope protects only the supplier.
Use one provider end to end
Splitting migration and ongoing support between two firms saves nothing and creates a handover nobody owns. Most UK businesses do better with managed IT services covering both, so the team that built the tenant is the team that lives with it.
Questions to ask before you sign
A quote is only comparable if you know what sits behind it. These questions expose the difference quickly.
Is discovery included, and what happens if it finds something?
The answer should describe a change-control process, not a shrug. A provider who has never been surprised has never looked hard enough.
Who owns the tenant?
The tenant should be registered to your business, with your named global administrator, regardless of who administers it day to day. This is non-negotiable.
What is the rollback plan?
Every stage needs one. “We will fix it forward” is not a rollback plan, and the cutover weekend is the wrong time to discover that.
How many hypercare days are included?
Ask for a number. Ask what happens on day eleven. A concrete answer here is the strongest signal that the provider has done this before.
Is out-of-hours work included in the price?
Cutovers happen at weekends. If evening and weekend rates are excluded, the quoted Microsoft 365 migration cost is not the one you will pay.
What does the ongoing monthly cost look like?
Licences, backup, support and any recurring tooling. If a provider will not put a run-rate figure alongside the project figure, the comparison is incomplete.
Frequently asked questions about Microsoft 365 migration cost
How much does a Microsoft 365 migration cost for a fifty-person business?
Between roughly £2,500 and £9,000 in professional services for a clean environment, rising to £9,000 to £28,000 where a file server, hybrid identity or legacy applications are involved. Licences are separate and recurring.
How long does a Microsoft 365 migration take?
Six to eight weeks is realistic for a well-run fifty-user project, of which only one weekend is disruptive. Micro businesses can be done in a fortnight; three-hundred-user estates typically run three to four months.
Can we migrate ourselves and avoid the cost entirely?
Technically yes for very small, simple environments. The risk is not the mail move but identity, permissions and the applications that relay email. A failed cutover costs more in lost days than the project fee it saved.
Does Microsoft charge for the migration?
No. Microsoft charges for licences. The Microsoft 365 migration cost you pay is professional services, plus any third-party tooling. Microsoft does publish its own mailbox migration guidance if you want to understand the mechanics.
Will there be downtime?
Properly planned, mail delivery is not interrupted — messages queue during the MX change and deliver afterwards. Users experience profile re-creation and a slow first sync rather than an outage.
Is any of this affected by UK data protection rules?
Data residency, retention and access control all need deciding, and the Information Commissioner’s Office guidance is the reference point. It rarely changes the Microsoft 365 migration cost materially, but it does change the design.
Turning the estimate into a decision
A credible Microsoft 365 migration cost is not a single number. It is a project fee, a licence run-rate, a backup subscription and a support arrangement, each of which you can compare properly once they are separated.
Build the three-year picture
Add the one-off fee to thirty-six months of licences, backup and support. That total is what you are actually choosing between, and it usually makes the licence conversation the important one.
Judge the plan, not the price
The cheapest quote with no discovery, no pilot and no rollback is not cheaper. It has simply moved the cost to a point where you have no negotiating position left.
Start with what you have
Whether you are moving from Exchange, from Google Workspace or from a tenant that has drifted, the first step is the same: an honest inventory. A good provider will do that before quoting, and their cloud adoption approach should make the reasoning visible rather than asking you to trust a total.
Get those three things right and the Microsoft 365 migration cost becomes a manageable, predictable piece of your IT budget instead of an unpleasant surprise halfway through a weekend.
