Medicare Cost Contract Extension and Refinement Act of 2003

Medicare Cost Contract Extension and Refinement Act of 2003 - Amends title XVIII (Medicare) of the Social Security Act (SSA) to: (1) extend reasonable cost contracts under the Medicare program and the period during which cost contracts may expand service areas; (2) apply certain Medicare+Choice requirements under Medicare part C (Medicare+Choice) to cost contracts to allow beneficiaries to be informed about the option of cost contracts, apply quality assurance requirements, prevent plans from discriminating against certain patients by offering lower premiums, and prohibit States from taxing cost contract premiums; and (3) permit dedicated group practice health maintenance organizations to participate in the Medicare cost contract program.