What does "IBNR" stand for in insurance terminology?

In insurance terminology, "IBNR" stands for Incurred But Not Reported. This term is vital in the context of reserving for claims. It refers to losses that have occurred but have not yet been reported to the insurance company. Insurers must estimate IBNR losses to ensure they have sufficient reserves to cover these claims when they eventually come in. Accurately calculating IBNR is crucial for financial reporting and for setting appropriate premiums to maintain the insurer's solvency. This practice reflects the need for insurance companies to account for all potential liabilities incurred during a specific period, even if the exact claims have not yet been formally communicated.