Do I need to buy EDR if my license is Business Premium?
Usually not. Business Premium already includes Defender for Endpoint — the question is whether anyone has switched it on.
This comes up on nearly every scoping call. A client is quoted a per-endpoint EDR product, and nobody has checked what their Microsoft license already covers.
Microsoft 365 Business Premium includes Defender for Business, which is a genuine EDR: behavioral detection, automated investigation and remediation, attack surface reduction rules, and web content filtering. Enterprise E5 goes further again with Defender for Endpoint Plan 2. If you hold either, buying a second EDR means paying twice for the same control, and running two agents that will occasionally fight each other.
So when would you buy something else?
There are real cases. The most common ones we see:
- Your plan is Business Basic or Standard. Neither includes advanced endpoint protection, so the device is running Defender Antivirus with no EDR behind it. Here you do need to add something — we use SentinelOne Control or Bitdefender GravityZone.
- You have a mixed estate with servers, Linux machines or unmanaged devices that fall outside the Microsoft licensing model.
- You need a specific capability Defender does not cover, or a compliance regime that names a particular product.
The part people miss
Owning the license is not the same as being protected. Defender ships largely switched off or half-configured. Onboarding has to be pushed to every device, attack surface reduction rules have to be set to block rather than audit, automated remediation has to be enabled, and exclusions left behind by a previous antivirus have to be cleaned out. We regularly find tenants where Defender has been licensed for two years and is protecting perhaps a third of the estate.
The other half is that EDR only helps if someone reads what it produces. An alert at 2am on a Sunday is only useful if a human is looking. That is a separate question from which product you own, and it is the argument for managed detection and response rather than for a second agent.
What we would do
Start with a license review. Count what you are paying for, check what is deployed, and close the gap before spending anything new. In most Business Premium tenants there is no reason to buy an EDR at all — there is a reason to finish configuring the one you have.