Medicare Dual Eligible Prescription Drug Coverage Act of 2005

Medicare Dual Eligible Prescription Drug Coverage Act of 2005 - Provides that, for prescriptions filled between January 1 and June 30, 2006, requirements for the coordination of prescription drug benefits with Medicare as primary payor for dual eligible individuals under the new prescription drug benefit program (PDP) under Medicare part E (Voluntary Prescription Drug Benefit Program) shall not apply. Requires a State to continue to provide Medicaid medical assistance with respect to prescription drugs as if such coordination requirements had not been enacted.

Declares that no State or the District of Columbia shall be required to pay (reimburse) the Secretary of Health and Human Services for Medicaid prescription drug costs for dual eligible individuals (Medicaid clawback payments) for any month before July 1, 2006.

Earmarks specified amounts for education and outreach to dual eligibles regarding prescription drug coverage and monitoring of their transition to prescription drug coverage under Medicare.

Requires a PDP sponsor and an MA organization offering an MA-PD plan to submit to the Secretary appropriate information regarding the drug utilization of enrollees in such plans who are full-benefit dual eligible individuals. Directs the Secretary to collect data on the drug utilization of full-benefit dual eligible individuals and share it with the States and District of Columbia in as close to a real-time basis as possible.

Directs the Comptroller General of the United States to study and report to Congress on the clawback formula.