Affordability in Medicare Premiums Act of 2004

Affordability in Medicare Premiums Act of 2004 - Directs the Secretary of Health and Human Services, for each year beginning with 2005, to reduce the monthly Medicare part B (Supplementary Medical Insurance) premium rate for each month in the year for individuals not enrolled in a Medicare Advantage plan and each individual enrolled under Medicare part B so that the aggregate amount of such reductions in the year equals an amount computed according to a specified formula involving reduced payments to Medicare Advantage organizations.

Requires the Secretary, in applying risk adjustment factors to payments to Medicare Advantage organizations, to ensure that such payments are adjusted to reflect the enrollee's health status, including adjusting for the difference between the health status of the enrollee and individuals enrolled under the original Medicare fee-for-service program under Medicare parts A (Hospital Insurance) and B. Requires payments to such organizations, in the aggregate, to reflect such differences.

Eliminates the MA Regional Plan Stabilization Fund (Slush Fund).