Military Survivor Benefits Improvement Act of 2004

Military Survivor Benefits Improvement Act of 2004 - Adjusts the basic Survivor Benefit Plan (SBP) annuity amount for surviving spouses, age 62 and older, of former military personnel to: (1) 35 percent of the retired pay of the decedent (current law), for months before October 2005; (2) 40 percent for months after September 2005 and before October 2008; (3) 45 percent for months after September 2008 and before October 2014; and (4) 55 percent for months after September 2014 . Adjusts similarly percentage amounts with respect to survivors of reserve personnel and survivors of persons who die while on active duty. Provides a corresponding phased elimination of the SBP supplemental annuity authorized to be provided to such surviving spouses. Requires periodic recomputation of: (1) annuity amounts beginning in October 2005; and (2) retired pay reductions for supplemental survivor annuities.

Provides a one-year open enrollment period for SBP participation, commencing October 1, 2005, for those currently not participating, those electing to increase current coverage, and those wishing to participate in the supplemental SBP.

Authorizes the Secretary of Defense to require appropriate premiums for SBP participation.