When does a BOC-3 expire?
A BOC-3 designation does not have a fixed expiration date. It stays valid indefinitely under 49 CFR Part 366, until the carrier replaces it (new agent), the underlying authority is surrendered, or the carrier's legal-name or MC-number identity changes. There is no FMCSA-required annual renewal.
The "expiration" question comes up most often because some BOC-3 vendors bill annually and frame the rebill as a renewal. That billing is the vendor's subscription model — it is not driven by an FMCSA expiration. The federal designation itself has no clock.
The four events that effectively "expire" a BOC-3 are all carrier-side: (1) filing a new BOC-3 with a different agent (replaces old), (2) carrier legal-name change on the MC (the old name on the BOC-3 no longer matches), (3) MC-number change after revocation and re-application (the old BOC-3 attached to the old MC), and (4) voluntary surrender of operating authority.
A process-agent-side event can also break a BOC-3: the agent withdrawing its BOC-91 registration (going out of business, retiring) orphans every BOC-3 referencing it. The carrier remains technically on file but service of process can no longer be routed. Refiling with a different agent is the clean fix.
For the practical "is my BOC-3 current" check, look at the FMCSA SAFER snapshot for your MC. The process-agent name appears under "Process Agent" in the carrier-information block. A blank or "INACTIVE" entry there is the signal that something has gone wrong and a refile is needed.