Because a claims-made policy generally requires a claim to be made (and, for claims-made-and-reported forms, also reported) while the policy is active, an insured who cancels, does not renew, or switches insurers faces a potential gap for conduct that occurred during the expired policy's term but is not claimed until afterward. Tail coverage, typically purchased as an extended reporting period endorsement, closes that gap by allowing claims first made during the tail period to still be covered as if made during the original policy term.

Tail coverage does not extend the underlying policy's coverage period for new conduct — it only extends the reporting window for claims based on conduct that occurred while the original policy was in force. It is commonly triggered by retirement, firm dissolution, a merger, or simply switching to a new claims-made carrier, and the cost (often a substantial percentage of the annual premium) is a frequent point of negotiation in professional transitions.

Juricratic keeps tail coverage and prior-acts coverage conceptually distinct in its modeling: tail coverage extends the reporting window on the departing policy, while prior-acts coverage extends the effective coverage start date on the new policy, and the simulation requires the user to specify which mechanism (if either) closes a given coverage gap rather than assuming one automatically substitutes for the other.

Professionals retiring, dissolving a practice, or switching malpractice carriers evaluate tail coverage cost against the residual risk of unreported claims for past conduct, often negotiating the tail purchase into the terms of a firm sale, merger, or partnership dissolution agreement.