Migrating from Active Directory to Entra ID means moving your user authentication and device management from an on-premises server to the cloud. Coreitech runs a 6-step migration (Audit → Plan → Pilot → Baseline → Full Migration → Handover) with zero downtime guaranteed, hybrid scenarios supported and UK-based Microsoft specialists managing every cut-over wave.
Active Directory to Entra ID Migration — UK
Migrate with zero downtime. UK-based Microsoft specialists.
4.9★ · Microsoft Solutions Partner · 6-step migration · Pilot + waves = zero downtime · UK engineering throughout
Coreitech plans and executes the move from your on-premises Active Directory to Microsoft Entra ID in sequenced waves — so your users keep logging in, your applications keep authenticating, and the old server infrastructure is decommissioned behind the scenes without anyone noticing.
Active Directory vs Entra ID — the key differences UK businesses need to know
| Feature | Active Directory (on-prem) | Entra ID (cloud) |
|---|---|---|
| Where it runs | On a Windows Server in your office | Microsoft's UK data centres |
| How users authenticate | Joined to the office network/domain | Anywhere via the internet |
| Device management | Group Policy Objects (GPO) | Intune (MDM/Endpoint Manager) |
| Works with | On-prem apps, file servers, printers | M365, SaaS apps, cloud services |
| Best for | Legacy apps that don't cloud-authenticate | Cloud-first/hybrid modern workforces |
Migration scenarios we support — from hybrid to cloud-only
Entra ID Connect
Sync identities from your on-prem AD to Entra ID. Good for phased moves where on-prem and cloud are both needed. Our default start point. We push sync, decommission the legacy identity layer and keep some file/print on-prem while moving apps forward.
Hybrid Azure AD Join
Devices are joined to both on-prem AD and Entra ID simultaneously. Users sign in once and access both. This is typically where your devices sit during the migration window — authenticated to both, no second login required.
Cloud-Only Entra ID
No on-prem AD at all. New devices join Entra ID directly. Users exist entirely in the cloud with Intune MDM and conditional access in place. Best for new businesses or ones that have already moved every dependency to the cloud.
Our 6-step Active Directory to Entra ID migration process
We review your current Active Directory environment — users, groups, GPOs, on-premises Exchange, file shares, and device join configurations — and identify which authentication and directory model fits your business
We review your current Active Directory environment — users, groups, GPOs, on-premises Exchange, file shares, and device join configurations — and identify which authentication and directory model fits your business: cloud-only Entra ID, hybrid with Entra Connect, or staged migration.
We produce a migration plan covering identity sync, group and policy mapping, device transition sequencing, application compatibility with Entra ID, piloted user groups, nomination of testers, rollback criteria, and the communication schedule — all against a single master plan.
We produce a migration plan covering identity sync, group and policy mapping, device transition sequencing, application compatibility with Entra ID, piloted user groups, nomination of testers, rollback criteria, and the communication schedule — all against a single master plan.
Before migration. MFA across all cloud services, conditional access policies, entitlement review for privileged Azure AD roles, and device enrolment through Intune. We never migrate onward to a new directory with an insecure starting posture.
Before migration. MFA across all cloud services, conditional access policies, entitlement review for privileged Azure AD roles, and device enrolment through Intune. We never migrate onward to a new directory with an insecure starting posture.
We migrate an agreed testing group first. Testing covers authentication, SSO, app sign-in, device enrolment and sync latencies. We record defects, remediate and re-test before proceeding.
We migrate an agreed testing group first. Testing covers authentication, SSO, app sign-in, device enrolment and sync latencies. We record defects, remediate and re-test before proceeding.
User groups, devices and applications are migrated in sequenced waves. We apply the plan and verify post-migration with automated and manual checks.
User groups, devices and applications are migrated in sequenced waves. We apply the plan and verify post-migration with automated and manual checks.
Legacy infrastructure decommissioned, on-prem AD demoted, synchronisation verified, and documentation handed over. Your users work normally while the old infrastructure is retired behind the scenes.
Legacy infrastructure decommissioned, on-prem AD demoted, synchronisation verified, and documentation handed over. Your users work normally while the old infrastructure is retired behind the scenes.
Why UK businesses trust Coreitech for Entra ID migrations
we deal directly with the teams building the platform you're migrating to
sequential, piloted — we never flip the entire organisation to a new identity platform overnight
your migration can stop at any stage and keep working; there's no all-or-nothing pressure
once migrated, every device adheres to the policy set and support is provided for 30 days to catch edge cases
AD to Entra ID migration — frequently asked questions
Q.What is the difference between Active Directory and Entra ID (formerly Azure AD)?
Active Directory (AD) is an on-premises directory service that runs on a Windows Server in your office. Entra ID (formerly Azure AD) is Microsoft's cloud-based identity and access service. AD authenticates to on-prem resources (servers, file shares, printers) via the office network. Entra ID authenticates to cloud services (Microsoft 365, SaaS apps) from anywhere. Modern organisations run both in a hybrid configuration, with most workloads increasingly favouring the cloud identity.
Q.Can I move from Active Directory to Entra ID without downtime?
Yes. The migration sequence we use — sync first (Entra ID Connect), pilot a sample group to validate everything works, then switch in managed waves — keeps your existing directory operational throughout. We use phased user/device migration with rollback thresholds — never flip and hope. The full process runs in parallel to your normal day and users are told exactly what to expect at each wave.
Q.What happens if something goes wrong during an AD to Entra ID migration?
Because we migrate users in waves with Entra ID Connect syncing passwords and identities continuously, a rollback to your original Active Directory is straightforward as long as you stay within the hybrid window. We set clear stop/go criteria before each wave. If a wave reveals a compatibility issue (most commonly an old app that won't authenticate to Entra ID), we remediate it before moving the next group — not after.
Q.Do on-premises file servers and printers still work with Entra ID?
Modern hybrid joined devices handle this well. With Hybrid Azure AD Join, your users sign in once and are authenticated to both cloud (Entra ID) and local (AD) services simultaneously — including on-premises file servers, printers and line-of-business apps. The device acts as authenticated to both directories until the on-prem resources themselves are migrated to Azure or SharePoint.
Q.How long does an AD to Entra ID migration take?
The time depends on three factors: the complexity of your existing AD (user and group counts, GPO mapping complexity, legacy dependencies), the number of applications that need testing against Entra ID, and the volume of on-premises infrastructure to retire. A simple environment with app compatibility verified can migrate within 2–4 weeks. A complex environment with custom apps, deep GPO boundaries and heavy file and print reliance can take 2–4 months. Each is scheduled against your risk preference and budget.
Q.Do you support AD migrations as a co-managed project with my internal IT team?
Yes. Many businesses with an in-house infrastructure person prefer the business to steer the planning and let Coreitech execute the cut-over waves and decommission the legacy. Other businesses want Coreitech to project-manage the entire sequence including the internal stakeholders — which also works. Decide where your team sits and we'll fit our side to yours.
Q.Is Entra ID migration included in my managed IT plan?
If you're an existing Coreitech managed IT client and you hold an Advanced plan, migration sequencing and project management of the Entra ID shift can be covered under your existing plan fee. For non-clients or businesses wanting basic-project migration under the Standard plan, the Entra ID shift sits as a quoted segment above your Standard price — typically quoted per user with the same fixed-price, no-surprise approach as everything else we do.
Q.Can you help with Entra Connect setup and troubleshooting?
Yes. Entra Connect (the sync tool connecting your on-prem AD to the Microsoft cloud) is Coreitech's core territory. Whether you're setting it up for the first time, troubleshooting sync failures or planning to replace a domain controller — that's a daily activity. We support all Entra Connect versions and the newer Entra Cloud Sync tool for simpler Lightweight Directory Access Protocol (LDAP) outlets.
Ready to move from Active Directory to Entra ID?
We assess your current environment, scope the migration precisely, and run it in waves — with zero downtime, phased roll-out and post-handover support.