We are modifying our regulations to clarify and revise what we consider major life-changing events for the Medicare Part B income- related monthly adjustment amount (IRMAA) and what evidence we require to support a claim of a major life-changing event. Recent changes in the economy and other unforeseen events have had a significant effect on many Medicare Part B beneficiaries. The changes we are making in this interim final rule will allow us to respond appropriately to circumstances brought about by the current economic climate and other unforeseen events, as described below.