Almost every permit tracker models one rule: a permit expires if work does not start within 180 days of issue. That rule is real, and it is also the one that rarely causes trouble — a contractor who pulled a permit generally starts the job. IBC 105.5 contains a second sentence that matters far more: once work has commenced, the permit becomes invalid if the work is suspended or abandoned for 180 days. That clock does not run from the issue date. It runs from the last time anything happened, and it restarts every time something happens again.
This is what kills permits in practice. A service upgrade gets roughed in and passes inspection in December. The customer stalls on a kitchen delivery, the job sits, and nobody calls the next inspection. The following June the permit is void — even though it was issued only seven months earlier and everyone involved believes it is live. A tracker that measures from the issue date would have shown that permit as comfortably active. This one measures from the December inspection and shows it expiring in June, which is the answer that lets somebody do something about it.
Two details follow from reading the rule carefully. A failed inspection has to count as activity: the inspector attended and the crew is working through corrections, which is the precise opposite of the suspension or abandonment the rule is aimed at. Treating a failure as nothing would show a permit dying while work is visibly underway. And a cancelled inspection has to not count, or a booking nobody attended could hold a dead permit open indefinitely. The builder draws that line explicitly, and prints which clock produced every date so the reader never has to guess.