Improved Military Medical Plan Act

Improved Military Medical Plan Act - Amends the Civilian Health and Medical Program of the Uniformed Services (CHAMPUS) to allow certain eligible beneficiaries to enroll in any health benefits plan under the Federal Employees Health Benefits Program (FEHBP) that offers medical care comparable to that offered under CHAMPUS. Includes as eligible beneficiaries any member or former member of the armed forces who is entitled to retired or retainer pay or its equivalent or would have been entitled to such pay except for having died before age 60, and any dependents of such individuals, who are also entitled to hospital insurance benefits under Part A of title XVIII (Medicare) of the Social Security Act.

States that any such beneficiary shall not be required to satisfy any FEHBP eligibility criteria as a condition for enrollment. Requires the Director of the Office of Personnel Management (OPM) to select the areas in which beneficiaries must reside in order to be enrolled in an FEHBP plan, including at least six regions of the TRICARE Program (a Department of Defense managed care program).

Outlines enrollment procedures, including a 90-day enrollment period. Requires FEHBP reimbursement of costs for the provision of treatment at a military medical facility. Outlines provisions concerning required beneficiary copayments under the FEHBP and Federal contributions to such plans. Provides for: (1) management of plan participation by the OPM Director; (2) annual reports from the Secretary of Defense, the Secretary of Transportation for the Coast Guard when not operating as a service in the Navy, the Secretary of Health and Human Services (the administering Secretaries), and the OPM Director concerning the provision of such care; (3) a report from the administering Secretaries on the advisability of either offering such care nationwide on a permanent basis or limiting such option to current eligible beneficiaries, the costs of such care, and their recommendations; and (4) a report from the Comptroller General, following the report from the administering Secretaries, assessing such recommendations.

Provides funding for FY 1999 through 2003 for the enrollment plan option, to be derived from amounts appropriated to the Departments of Defense, Transportation, and Health and Human Services.

Directs the administering Secretaries to report to the Congress a plan for any enhancements of the health care options under the TRICARE program known as TRICARE Standard considered necessary to ensure that coverage under such option is substantially similar to coverage offered under the FEHBP fee-for-service health benefits plan that has the most subscribers as of the date of the report.