Incurred but not reported

In insurance, incurred but not reported (IBNR) claims is the amount owed by an insurer to all valid claimants who have had a covered loss but have not yet reported it.

[1][2] The term "IBNR" is sometimes ambiguous, as it is not always clear whether it includes development on reported claims.

For example, when a claim is first reported, a $100 payment might be made, and a $900 case reserve might be established, for a total initial reported amount of $1000.

The estimated amount of this future development on reported claims is known as IBNER.

Since the implementation of Solvency II, stochastic claims reserving methods have become more common.