What happens when a badge is lost?
Whatever your procedure says, because the procedure is the security control rather than the card. Revocation itself is instant in any competent system. The exposure is the time between losing the badge and somebody being told, and that is entirely human.
The gap that matters
From the moment a badge is lost to the moment it is revoked, it works exactly as it did before. The system has no way to know.
That gap is where the entire risk sits, and it is measured in hours or days rather than in anything technical.
People delay reporting because they hope to find it, because reporting is inconvenient, or because they do not realise it matters.
So the security question is not how good the card is. It is how quickly someone tells you.
Revocation is the easy part
In a managed system, withdrawing a badge is a single operation and takes effect at the next check.
Where readers hold local copies for offline operation, effect depends on how often they update, which is worth knowing rather than assuming.
A badge revoked at a central system and still accepted at a door for hours is a real and common gap in offline capable installations.
Ask how long that takes, in exact terms, and test it once rather than trusting the answer.
What the procedure must cover
Who to tell, available outside office hours, since badges are lost at weekends.
That reporting a loss carries no penalty, because a procedure people avoid is a procedure that does not work.
What happens to the person meanwhile: a temporary badge, an escort, or a documented exception. Someone with no route in will find one, and it will not be the route you designed.
What happens if the badge is found afterwards, which is common and needs a decision rather than an improvisation.
And a record of every revocation, since that log is what an audit examines.
Reducing the gap
Make reporting trivial: one number, one form, no explanation required.
Separate the badge from things people notice losing. A badge on a lanyard round a neck is missed within minutes, and one in a wallet may not be missed for a day.
Review dormancy. A badge unused for an unusual period is worth a question, and that is a report the system can generate rather than a person noticing.
And do not put the address of the building on the badge. A found badge that identifies its own door is a considerably more useful object to whoever finds it.
Frequently asked questions
How fast can a badge be revoked?
Centrally, immediately. At the door it depends on how often readers update when they operate offline, which is worth testing rather than assuming.
Should losing a badge carry a penalty?
No. A penalty delays reporting, and the delay is the entire risk. Make reporting easy and consequence free.
What if the badge turns up later?
Decide in advance whether it is reactivated or destroyed. Improvising this is how revoked badges quietly return to circulation.
Should the building address be printed on it?
No. A found badge that identifies its own door is far more useful to whoever finds it.