The shadow behind you: tailgating – an expensive security nightmare
December 8, 2025
You've probably done it yourself. Someone’s fumbling with their keycard at the office or building entrance, and you slip in right behind them with a friendly “thanks!” It feels harmless; neighbourly, even. After all, you work there too, right? But what you’ve just witnessed (or participated in) is one of the most underestimated security threats facing businesses (and apartment/condo dwellers) today.
Tailgating.
The practice of following someone through a secure entrance without proper authorization might seem innocuous, but security experts consider it a gateway to far more serious breaches. And here’s the uncomfortable truth: our natural human instincts, the very politeness that makes us hold doors open for others, are being weaponized against us.
The psychology of following
Unlike the high-tech hacking scenarios we see in movies, tailgating exploits something much more fundamental: our social conditioning. We’re raised to be courteous, to hold doors, to not slam barriers in people’s faces. This creates what security professionals call a “social engineering vulnerability” - a weakness that exists not in our technology, but in our humanity.
The mechanics are simple. An unauthorized person approaches a secure entrance just as an employee or resident is entering. This person might be carrying coffee, talking on their phone, or simply walking with confidence. Not wanting to appear rude or suspicious, we allow them to follow through the door. Mission accomplished.
But the implications are anything but simple. Once inside, that unauthorized person has bypassed potentially thousands of dollars’ worth of security infrastructure: keycards, biometric scanners, surveillance systems, with nothing more than good timing and social manipulation. The average cost when this happens to a Canadian company and leads to a data breach? $7 million.
“Tailgating or piggybacking by an unauthorized person at business offices occurs so often that it is one of the most frequent physical security breaches in commercial environments,” says Senad Cehajic, Director, Business Continuity and Corporate Security at OMERS. “The most typical outcome of tailgating is unauthorized access to sensitive areas such as executive offices, conference rooms and server rooms, which could all result in a negative disruptive impact to the organization.”
Beyond the office: the residential risk
While businesses have been grappling with tailgating for years, the problem has expanded far beyond corporate environments. Residential buildings, particularly condos and apartment complexes, face similar vulnerabilities. That person following you into your building's lobby might not be visiting a friend on the third floor. They could be scouting for unlocked doors, packages to steal, or worse.
The RCMP reports that residential security breaches often begin with unauthorized building access, with tailgating being a primary method of entry. Unlike commercial spaces with dedicated security personnel, residential buildings typically rely on residents themselves to maintain security protocols. This distributed responsibility creates gaps that bad actors can easily exploit.
Consider the psychology at play: when someone is struggling with groceries at your condo’s entrance, your instinct is to help. When a delivery person is waiting outside with packages, letting them in feels like the right thing to do. These moments of everyday courtesy become security vulnerabilities.
The Escalating Consequences
What starts with someone slipping through a door can escalate quickly. Once inside a building, unauthorized individuals can:
Access sensitive areas and information
Install malicious hardware or software
Conduct reconnaissance for future attacks
Steal physical assets or personal information
Compromise the safety of legitimate occupants
For businesses, this translates to potential losses in the millions. For residential buildings, it means compromised safety for families and individuals who believed they were secure in their homes.
“The most effective preventive measures to combat tailgating begin with security training awareness for employees,” adds Senad. “Another very effective measure is an access control system at all external and internal points of entry to a building, including elevators. Visitor management protocols and surveillance systems further augment anti-tailgating measures.”
Building a culture of security
The solution isn’t to abandon common courtesy, it’s to create systems and cultures that balance politeness with security. Successful organizations implement “challenge protocols” where employees are trained to feel fully comfortable to politely but firmly verify that unfamiliar individuals have proper authorization. This might feel awkward initially, but it becomes second nature with practice.
For residential buildings, the approach needs to be community-focused. Residents must understand that asking “Can I help you find someone?” isn't rude, it’s responsible. Building managers can install visual cues, like signs reminding residents about tailgating risks, and implement policies that make security everyone’s responsibility.
The human firewall
Technology will continue to evolve via facial recognition systems, advanced keycards and biometric scanners. But the most sophisticated security system is only as strong as the humans who use it. In our interconnected world, where physical and digital security threats increasingly overlap, it’s about recognizing that sometimes, the most dangerous threats come not from sophisticated hacking tools or complex schemes, but from someone simply walking through a door behind you.
Because in security, as in life, the devil is often in the details; and sometimes, those details are as simple as not letting strangers follow you home.
The Relatable Economist is an ongoing written series focused on how the economy, geopolitics, markets and more are impacting our day-to-day lives, discussing topics that matter to you, even if just to share with your friends at your next get-together or in the stands at your child’s or grandchild’s soccer game. Have a topic you want to learn more about? Write to us at therelatableeconomist@omers.com.