The work analyses, through recourse to the comparative method, the processes for the temporal delimitation of the risk developed in the face of the emergence of an increasing number of cases of damage marked by a considerable time lag between the production and the manifestation of the prejudice in the legal sphere of the injured party, in open contrast with the need, underlying the insurance technique, to be able to calculate the premium with precision, having regard to the frequency and magnitude of the loss occurrence covered. The attempt is to identify the origins, structure and functional profiles of the risk management technique that the insurance market has developed in order to overcome such ciriticities, namely the policies on a claims made basis. In fact, they represent, in practice, the only contractual option available to customers wishing to provide cover for third party liability arising from activities potentially giving rise to long-tail claims. Paolo Tortorano, researcher in Comparative Private Law at the Department of Political Science of the University of Campania Luigi Vanvitelli, is lecturer in Legal Systems Convergence. He authored numerous publications on Comparative Law and Insurance Law, published both in Italy and abroad.