What is Anti Passback?

Prevent the passing back of access credentials


Two people showing how anti passback works
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What is anti passback in access control?

What is anti passback? – Anti passback (APB) security measures prevent successive entries by multiple people with the same access card, preventing ‘passing back’ of the same access card. The measure prevents keycard misuse and unauthorized access.

There are various iterations of the APB measure, including soft, hard, area, and timed anti passback measures. Deciding which variant of anti passback access control is right for your business is dependent on your security requirements.

Types of Anti Passback

Hard Anti Passback

When the anti passback rule is violated, the cardholder will be denied access.

Soft Anti Passback

A violation of the APB rules will result in granted access, but administrators of the system will receive an alert of the incident and the associated cardholder.

Area Anti Passback

Until a card is used at an ‘in’ reader at the entrance to the building, the card will not work at any readers inside the building.

Timed Anti Passback

Once a card has been used to enter an area, it cannot be used at the same reader again until the defined time period has passed, for example, 15 minutes.

Having reviewed the types of anti passback available, let’s look at how it works…

Anti passback works by recording who has entered and exited a specific area. This is achieved via access cards that have to be used in conjunction with an access reader from the access control system. Every time a card is used to enter, it must be used to exit before it can be used to enter again.

An easy way to imagine this is through the following example:

Person A works in a building and has a valid access card to gain entry to the building. Person B wants to gain entry to the building, but has no valid credential to do so. Person A and Person B approach the entrance and Person A swipes their access card, which grants them entry to the building. Person A then passes their credential back to Person B, who swipes the same card on the same reader, but is denied entry due to the anti passback measures on the reader. An alert is sent to the administrator to let them know of the violation of the anti passback rule.

By swiping or tapping into an area, the user temporarily revokes their access, preventing them from re-entering with their credential until they have exited the area by swiping or tapping the corresponding reader. Therefore, in passing their credential back to the unauthorized person, the second use of the card to gain access is denied.

A popular application of APB is at parking gates. In these settings, a user swipes their card when entering and exiting the lot. The user can enter and exit as many times as they desire, as long as the sequence remains as an ‘in and out’ pattern. However, if a user were to enter and then pass their card back to their colleague/friend/neighbor, the pattern becomes ‘in and in’, which the anti passback measure will reject and deny access to the second request for entry. Until that card has been used to exit the lot, the system will not allow entry.

Example applications of anti-passback

Anti-passback is commonly used in parking facilities. However, it has multiple useful applications, such as office entrances, specifically employee entrances.



Protect patients, staff, and expensive equipment with anti-passback. By preventing multiple drivers from using the same access credential, parking spaces can be kept safe. Ensure only authorized cardholders can enter certain areas of the facility.


Fitness Facilities

Prevent customers from sharing credentials and skipping membership fees. Integrate with turnstiles or gates to ensure capacity limits are adhered to and only paying users can access the facility.


Parking Lots & Multi-Storey

Ensure accurate parking space counting, preventing too many cars from entering the parking lot. Prevent unauthorized vehicles from entering a certain parking area.


Holiday Facilities/Parks

Anti-passback ensures that only authorized guests can access your facility. Access cards cannot be passed from paying guests to unauthorized persons at the perimeter barriers to access your facility free of charge.



Prevent employees from sharing credentials to access the building. Improve security and safety for employees, ensuring that unauthorized persons cannot tailgate or follow your employees into the building. Provides accurate information on employee attendance.



Anti-passback provides accurate occupant information, preventing unwanted personnel from entering or removing laboratory equipment. Optimize safety and stop potentially hazardous accidents from occurring.

Anti-Passback with Keri Systems

Keri Systems’ Doors.NET software integrates customizable anti-passback security measures, ensuring that you can use the feature in the most effective way for your building or facility. Keri Systems offers all types of anti-passback measures and allows for full flexibility when applying these rules. For example, certain cardholders can be exempt from anti-passback rules, whereas others can have hard or soft, timed or area APB ruling depending on their role or access needs.

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