Microsoft Defender for Business: Setup and Managed Service

It is one of the most capable controls inside Microsoft 365 security, and it only earns its keep when someone watches it. That is the gap most SMEs miss: the licence gives you the engine, not the driver. One provider. Security-first. Microsoft-certified.

What is Microsoft Defender for Business?

Microsoft Defender for Business is a dedicated endpoint security suite built for organisations with up to 300 users. It delivers enterprise-grade protection — next-gen antivirus, EDR, threat and vulnerability management, automated investigation, and attack surface reduction — from a single cloud console, designed so smaller teams get capability previously reserved for large enterprises (Microsoft Learn).

The 300-user cap is a hard product boundary. Above it, organisations move to Defender for Endpoint Plan 2. Below it, Defender for Business gives most UK SMEs the strongest endpoint control they can buy without enterprise licensing.

• Next-generation antivirus — behaviour-based malware blocking, not just signatures
• Endpoint detection and response (EDR) — detects, investigates and contains active attacks
• Threat and vulnerability management — surfaces unpatched, exploitable weaknesses
• Attack surface reduction (ASR) — rules that block common ransomware and macro attack paths
• Automated investigation and remediation — self-heals routine threats without an analyst

What's included in AMVIA's managed Defender service?

AMVIA's managed Defender for Business service covers the full lifecycle: design, deployment, tuning and 24/7 monitoring. We do not just switch the licence on — we configure ASR rules, set automated remediation, investigate every EDR alert through our UK SOC, and report monthly on what we caught and fixed.

• Security baseline — we assess your current endpoint posture and design Defender policies to your risk profile and compliance needs
• Deployment — Defender is rolled out across endpoints via Microsoft Intune or Group Policy, with ASR rules enabled
• Tuning and testing — detection sensitivity is calibrated and automated remediation validated against test scenarios
• Managed monitoring — our SOC investigates alerts, contains confirmed threats and escalates within an hour for critical issues
• Monthly reporting — clear posture reporting on detections handled and recommended improvements

This sits alongside our broader managed cybersecurity practice, so endpoint protection is never a silo — it feeds the same monitoring and response team that watches your email, identity and network.

Why do UK SMEs need managed Defender for Business?

Endpoints are where most breaches land. 43% of UK businesses identified a cyber breach or attack in the past year, and phishing was by far the most common vector (DSIT Cyber Security Breaches Survey 2025). Defender for Business is built to stop exactly those attacks — but only if its alerts are watched.

An unmonitored EDR tool is a smoke alarm with no one home. Defender will detect a ransomware precursor at 2am; whether anything happens next depends on who is watching. That is the difference between a licensed control and a managed service.

• Around 85% of breached UK organisations reported phishing as an attack type
• An estimated 19,000 UK businesses were hit by ransomware in the past year
• The average cost of the most disruptive breach to affected UK businesses was around £3,550

Defender for Business directly counters these: ASR rules block the macro and script paths phishing relies on, EDR catches ransomware behaviour early, and AMVIA's SOC turns a detection into a contained incident.

Licensed vs AMVIA-managed Defender: what's the difference?

The licence and the managed service are not the same purchase. Microsoft sells you the technology; AMVIA runs it. The table below shows what changes when a UK SOC sits behind the console.

Most SMEs do not have an analyst free at 2am. That is the value AMVIA adds — the same logic behind layering Defender with managed detection and response when risk is elevated.

How much does Microsoft Defender for Business cost?

Defender for Business is included at no extra cost in Microsoft 365 Business Premium, or available as a standalone add-on at around £2–3 per user per month (Microsoft list price, 2026) for firms on Business Basic or Standard. AMVIA's management fee sits on top of the licence and is quoted per environment after a short assessment.

For most UK SMEs already paying for Microsoft 365, the cheapest path to strong endpoint security is moving to Business Premium rather than buying the add-on separately — we model both before recommending one. See our Business Premium vs Standard comparison for the licensing trade-off, or book a Microsoft 365 security audit to confirm what you already own.

Microsoft's published UK list prices are Business Basic £4.60, Business Standard £9.60 and Business Premium £16.90 per user per month, ex VAT on an annual plan (Microsoft 365 UK pricing).

Why choose AMVIA for Microsoft Defender for Business?

AMVIA manages security and IT for 1,200+ UK businesses across legal, finance, healthcare and professional services. We are a security partner, not a telecoms reseller — Defender is configured by Microsoft-certified engineers and watched by our own SOC, not subcontracted out.

• Cyber Essentials Plus certified and a Microsoft Solutions Partner (Modern Work, Security, Infrastructure)
• Sheffield-based UK SOC — engineers who understand UK compliance and the threats facing British SMEs
• Sub-one-hour response to critical issues, by phone, email and portal, with a named account team
• 1,200+ UK businesses protected, rated 4.8/5 by clients