Most professional liability policies (including all accountant and lawyer policies sold in the United States) are Claims Made or Claims Made and Reported. The insurance carrier that carries the current coverage is liable for the claim when the claim is reported, not when the act occurred. Versus an Occurrence (Auto, Home, Business Owners coverage, etc) policy where the insurance carrier that was on the risk when the act occurred is liability for the claim regardless of when it was reported. The major importance of this is to continue to have coverage for Prior Acts in the future, an insured needs to have continuous Claims Made coverage in order to maintain their Prior acts date or have an Extended Reporting Period or Tail purchased to cover the acts in the past. Shortening or losing their prior acts date and coverage will expose the entity to uninsured losses.