If your computers run Windows 11, the antivirus subscription you’re paying for is almost certainly redundant. Microsoft Defender — the security tool already built into the operating system at no additional charge — performs as well as or better than the paid options most small businesses are still subscribing to. That’s the easy part of this answer. The harder part is that Defender isn’t enough on its own, and stacking another antivirus product on top of it doesn’t fix that problem. The thing you actually need is a different category of tool entirely, and most small businesses are underspending on that while overspending on a subscription that stopped earning its keep years ago.
Paid antivirus stopped making sense a few years ago
For most of the last two decades, the standard advice was simple: install Windows, then install a real antivirus. The built-in tools were thin, slow to update, and didn’t catch much. Norton, McAfee, Bitdefender — there was a market because there was a gap to fill.
That gap closed. Microsoft has spent the last several years pouring serious engineering into Defender, and the results show up consistently in independent testing. AV-TEST, AV-Comparatives, and SE Labs — the labs that everyone in security cites when they want to argue their product is best — regularly rank Defender at or near the top for both detection rates and false positives. In AV-TEST’s most recent consumer evaluations through early 2026, Defender has scored a perfect 6/6 across protection, performance, and usability for ten test cycles in a row. In AV-Comparatives’ March 2026 real-world malware test, the gap between Defender and the highest-scoring paid product was eight in ten thousand samples. That difference is statistically real and practically irrelevant for any small business that isn’t downloading thousands of unknown files a month.
If you’re paying for a third-party antivirus on Windows 11 because someone told you Defender wasn’t good enough, that someone was either out of date or selling you something. Both happen often enough in this industry that we’ll mention it directly: a lot of MSPs recommend whichever security product pays the best referral fee, and antivirus subscriptions have been one of the more reliable kickbacks in the business for years. We don’t take those, which is partly why we’re comfortable telling you to stop paying for something you don’t need.
A side note on Kaspersky, which used to belong on every list like the one above. The US banned the sale of Kaspersky products in 2024 over national security concerns, and Canada restricted its use on government systems even earlier. If your business still has Kaspersky installed somewhere — and it’s surprising how often we find it on machines that haven’t been touched in a couple of years — that’s worth uninstalling regardless of where you land on the broader paid-antivirus question.
Why running two antivirus products is worse than running one
Some readers, having heard the above, will reasonably ask: why not run both? Defender for free, plus a paid product for extra coverage. Belt and suspenders.
It doesn’t work that way. Antivirus products are designed to sit deep in the operating system and intercept everything that happens — file reads, network connections, process launches. When two of them try to do that simultaneously, they fight. They flag each other’s activity as suspicious. They slow the machine down, sometimes dramatically. Detection rates can actually drop because each product is interfering with the other’s ability to scan cleanly. This isn’t theoretical, which is why most third-party products will deactivate Defender automatically when you install them. You’re not getting two layers of protection. You’re getting one layer that works less well than either would on its own.
So the choice isn’t “Defender or Defender plus something.” It’s “Defender, or something instead of Defender.” And once you’re framing it that way, the question becomes whether anything available on the consumer or small-business antivirus market in 2026 is meaningfully better at the core job than what you already have running. The honest answer is no.
What antivirus — any antivirus — can’t do
Here’s where the conversation usually gets oversimplified. People hear “Defender is enough” and walk away thinking they’re covered. They aren’t.
Antivirus, in any form, looks for one thing: malicious software. It examines files and processes and asks whether they match something already known to be bad, or behave in ways known to be dangerous. When the answer is yes, it blocks. When the answer is no — because the threat is new, or because it doesn’t look like malware at all — it doesn’t.
A large share of modern attacks fall into that second category, and the share is growing. Phishing emails that trick someone into typing their password into a fake login page never trigger antivirus, because no malware is ever involved. AI-generated phishing has made these emails substantially harder to spot than they were even two years ago — the obvious tells are gone, the grammar is clean, the tone matches the supposed sender. Ransomware operators increasingly use legitimate, signed remote-access tools to move through a network, because those tools won’t be flagged. Compromised credentials get used to log in through the front door — VPN, email, Microsoft 365 — and antivirus has no visibility into any of it. Misconfigurations in your firewall or your tenant don’t involve software at all, but they’re how a lot of breaches actually start.
This isn’t a flaw in Defender. It’s a flaw in thinking about antivirus as the answer. Antivirus solves one specific problem — recognizable malicious software running on a machine — and it solves it well. The trouble is that “recognizable malicious software running on a machine” is no longer the way most attacks against small businesses work.
What actually fills the gap
The category of tool that picks up where antivirus leaves off is called endpoint detection and response, or EDR. The name is dry, but what it does is straightforward: instead of just checking files against a list of known threats, EDR watches what’s happening on each computer in real time and looks for patterns of behavior that suggest something is going wrong. A user account that suddenly starts encrypting files in bulk. A legitimate program being used in an unusual way. A process spawning child processes it shouldn’t. An attacker moving laterally from one machine to another. EDR sees these things, alerts on them, and in most modern implementations can isolate the affected machine before the damage spreads.
Run alongside Defender — not on top of it — EDR catches the things antivirus is structurally unable to catch. It’s a different tool solving a different problem, which is why adding it makes sense in a way that adding another antivirus does not.
There’s a 2026 nuance here that didn’t exist a few years ago, and it matters for small businesses specifically. EDR generates alerts. Someone has to read those alerts, decide which ones are real, and respond when they are. That someone needs to be available at three in the morning on a long weekend, because that’s when ransomware operators prefer to start. Most small businesses don’t have a security team. Most don’t have anyone in-house who can tell a real alert from a false positive at any hour, let alone the bad ones. Buying EDR software and pointing it at your network without anyone watching the dashboard is a common mistake, and an expensive one — the software is doing its job, but no one is doing theirs.
The version of EDR that actually works for a small business is the managed kind, sometimes called managed EDR or MDR. The technology is the same; what’s different is that a security operations team is watching it on your behalf, around the clock, and is empowered to take action when something real shows up. This is the layer that catches the threats that close companies down, and it’s where most of the meaningful security spend should go for a small business in 2026.
The rest of the picture
Endpoint detection covers what’s happening on your computers, but plenty of attacks never touch your computers in the first place. They go after your accounts.
Multi-factor authentication on everything that supports it — email, banking, remote access, cloud apps — does more to prevent breaches at most small businesses than any piece of security software you can buy. It’s free or close to it, and it’s still the single highest-impact step most companies haven’t fully rolled out. We see this constantly: MFA enabled on the owner’s email and nowhere else, or enabled in Microsoft 365 but not on the VPN, or set up months ago and never enforced after the latest hire. The full rollout is the part that matters.
DNS filtering, which blocks connections to known-malicious domains before they even load in a browser, is similarly cheap and disproportionately effective — particularly against the AI-generated phishing problem mentioned above, where the email gets harder to spot but the destination domain is still fresh and known to be bad. Patching — keeping Windows, your browsers, and your business software up to date — closes the holes that attackers actually use, because most successful intrusions rely on vulnerabilities that have been public and patchable for months.
None of these things are flashy. None of them have a slick marketing pitch. They are also, collectively, what protects a small business from being shut down for a week by ransomware. Antivirus is part of that picture. It isn’t the picture.
What this means for your IT budget
If you’re paying for third-party antivirus on Windows 11 machines, you can stop. Cancel the subscription, uninstall the product, let Defender do what it’s already doing well. That’s money you’ve been spending on a problem that’s already solved.
What to do with that budget instead is a longer conversation, but the short version is straightforward: spend it on the things antivirus can’t do. Managed EDR if you don’t have it, or a real conversation about whether your existing EDR is being watched by anyone. MFA enforced on every account that supports it, not just the obvious ones. DNS filtering. A patching process you actually trust. These are the layers that matter, and most small businesses we talk to are underspending on them while overspending on the antivirus subscription that’s been quietly redundant for years.
The question isn’t whether you have antivirus. The question is what happens when antivirus isn’t the part that fails.