Final answer:
An occurrence policy provides coverage for events that happened during the time the policy was in effect, regardless of when a lawsuit is brought forth, and usually costs more without needing tail coverage.
Step-by-step explanation:
The type of professional liability coverage described in the question, which covers an incident if you were insured when the event occurred regardless of when the lawsuit is filed, is known as an occurrence policy. This is contrasted with a claims-made policy where the policy must be active both when the event took place and when the lawsuit is filed. An occurrence policy generally costs more because it provides broader coverage over a longer time frame and does not require tail coverage (an additional policy that extends coverage after the policy expires). Unlike these policies, an umbrella policy provides extra protection beyond what's offered in the original policy's limits, while an excess liability policy increases coverage limits but doesn't broaden the range of covered incidents.