IBNR (Incurred But Not Reported) claims are cases, which have already occured, but not been reported to the insurer. Since the underlying
circumstances are unknown in principle, the corresponding costs can be considered only on a portfolio basis.
In connection with IBNR claims the term IBNER (Incurred But Not Enough Reserved) is often mentioned,
which refers to future payments for known claims, that have not been considered in the current case reserves.