Medicare Part D Improvement Act of 2007

Medicare Part D Improvement Act of 2007 - Amends part D (Voluntary Prescription Drug Benefit Program) of the Social Security Act to revise requirements for the Medicare prescription drug program with respect to: (1) counting certain expenditures towards out-of-pocket limits; (2) conforming the late enrollment penalty to the Medicare part B penalty structure; (3) allowing more frequent changes in plans; and (4) removing the asset test and eliminating late enrollment penalties for low-income subsidy eligible individuals.

Directs the Secretary of Health and Human Services to study and report to Congress on how to: (1) eliminate the gap in Medicare part D prescription drug coverage created through the application of an initial coverage limit; and (2) finance such elimination.