Guard and Reserve Enhanced Benefits Act of 2004 - Provides for benefits for members of the National Guard and Reserves who serve extended periods on active duty, including special assistance to them and their families through: (1) family leave, under the Family and Medical Leave Act of 1993; (2) child care, under the Child Care and Development Block Grant Act of 1990; (3) educational assistance, under Federal law relating to Montgomery GI Bill benefits; (4) student loan deferments, under the Higher Education Act of 1965; (5) preservation of educational status and tuition, under the Servicemembers Civil Relief Act; (6) non-reduction in pay in the case of those who are Federal employees, under Federal civil service law; (7) a tax credit to their employers for the income differential between their wages and their military pay, or a self-employment credit, under the Internal Revenue Code; (8) reduced minimum age for non-regular service retired pay, under Federal law relating to the Armed Services; and (9) health benefits, through expanded eligibility for the TRICARE program and continuation of non-TRICARE plan coverage for dependents, under Federal law relating to the Armed Services.