National Guard and Reserve Comprehensive Health Benefits Act of 2003

National Guard and Reserve Comprehensive Health Benefits Act of 2003 - Makes members of the Selected Reserve and the Individual Ready Reserve eligible for either the Prime or Standard option of the TRICARE Program (a Department of Defense managed health care program), allowing for either self-coverage or self-and-family coverage. Requires the Secretary of Defense to: (1) provide at least one open enrollment period each year for such members; and (2) charge applicable premiums, deductibles, and copayments for such coverage.

Directs the Secretary of the military department concerned to pay the applicable premium to continue in force any qualified health plan coverage for a reserve member (and his or her dependents) while the member is serving on active duty pursuant to a call or order issued during a war or national emergency declared by the President or Congress. Requires the continuation of COBRA coverage during such period. Prohibits simultaneous coverage under both the qualified health plan and TRICARE.