The most expensive antivirus is not automatically the best protection. A properly configured free Defender often beats a paid product that nobody manages - here is the honest comparison.
Every office owner faces the salesman question: is the built-in Microsoft Defender enough, or do we need to pay for antivirus? The truthful answer has two parts. Defender itself is a genuinely strong antivirus - independent tests rank it with the best. What paid products really sell is not stronger scanning; it is central management, alerts and EDR - behaviour-based detection and response across all machines from one console. This page separates the marketing from the substance so you can decide for your office size.
Defender is built into Windows 10 and 11 at no extra cost. It includes real-time scanning, cloud-delivered protection that reacts to new threats within minutes, ransomware-controlled folder access, and Tamper Protection that stops malware from disabling it. For a single PC or a very small office with someone who actually checks it, this is a complete antivirus.
Paid business products add three things Defender alone (without Microsoft's enterprise licences) does not: one console showing every PC's status, alerts when something is found or switched off, and EDR features - watching program behaviour, isolating an infected machine from the network with one click, and rolling back ransomware changes on some products. None of this makes the basic scan dramatically better. It makes protection visible and manageable across 10, 30 or 100 machines.
Use this simple split. Up to about 5 PCs, with one responsible person checking weekly: Defender, properly configured, is a defensible choice - spend the saved money on backup instead. Beyond that, or with no IT person: a paid business antivirus or EDR with a central console earns its price, because unmanaged protection quietly rots - licences expire, agents get removed, alerts go unread.
New PCs ship with 30-day trial antivirus. When it expires, many offices assume Defender takes over. Often it does not - the dead trial stays registered as the provider, Defender stays passive, and the PC runs effectively unprotected while showing an antivirus icon. Check every new PC on day one: either buy the licence or uninstall the trial fully so Defender activates. This single check closes one of the most common holes in small offices.
See the complete security setup live - firewall, endpoint, antivirus and backup, all in one video.
Watch Full VideoFor detection quality, yes - it consistently scores with top products in independent testing. What free Defender lacks for a business is central reporting and response tools across many PCs, which is the real reason offices buy paid products.
Normal antivirus asks, is this file known to be bad. EDR also watches behaviour - a program suddenly encrypting hundreds of files, or a Word document launching system tools - and can isolate the machine automatically. It catches newer attacks that have no known signature yet.
Probably not. An expired product usually stops receiving updates, and while it remains installed, Defender may stay in passive mode. Either renew it properly or uninstall it completely and confirm Defender shows all green.