Microsoft Defender for Business vs Third-Party MDR: Which Is Best for SMEs?

Defender for Business is a capable EDR tool included in M365 Business Premium, but it generates alerts that require skilled analysts to triage and act upon. Without dedicated security staff monitoring those alerts around the clock, threats can go unaddressed for hours or days. With 43% of UK businesses experiencing a breach or attack (DSIT 2025), the gap between detection and response is where most damage occurs.

Yes. Many MDR providers, including AMVIA, build their managed service on top of Microsoft Defender for Business. The MDR team monitors Defender's alerts, investigates suspicious activity, and takes containment actions on your behalf. This approach maximises your existing M365 Business Premium investment rather than replacing it with a competing endpoint agent.

Defender for Business is included in M365 Business Premium at approximately £16.60 per user per month. Adding MDR typically costs an additional £8 to £15 per endpoint per month. The alternative is hiring an in-house security analyst at £45,000 to £65,000 per year, making MDR significantly cheaper for SMEs with fewer than 200 endpoints.

Defender may quarantine known malware automatically, but sophisticated attacks — credential theft, lateral movement, living-off-the-land techniques — generate alerts requiring human judgement. Only 40% of UK businesses have two-factor authentication enabled (DSIT 2025), and unmonitored alerts from identity-based attacks often go unactioned until significant damage has occurred. MDR ensures every alert receives a human response.