What happens if my certificate expires?

When a certificate expires, whatever it vouches for stops being trusted, and the consequences land immediately. An expired SSL/TLS certificate makes browsers show a full-page security warning that scares off visitors; an expired professional certification can suspend your right to practice or bid on work; an expired compliance certificate (ISO, safety, insurance) can void contracts and fail audits.

The frustrating part: expiry is the single most preventable business failure there is. The date is known, often years in advance, and renewal usually just needs lead time for paperwork, audits or payment. Most expiry disasters are tracking failures, not renewal failures. A dated reminder set well before the deadline (30/60/90 days, depending on how slow the renewal process is) turns this from an emergency into routine admin.