Combat Veterans Pre-Enrollment Act of 2025This bill requires the Department of Veterans Affairs (VA) to establish a program to carry out all activities necessary to permit certain members of the Armed Forces to elect to enroll in the VA health care system on the date of separation of such members from active service. Specifically, the program is for those who served on active duty in a theater of combat operations during a period of war after the Persian Gulf War or in combat against a hostile force during a period of hostilities after November 11, 1998.The VA must, in conjunction with the Department of Defense (DOD) and Department of Homeland Security, establish a mechanism to permit a member of the Armed Forces to elect to pre-enroll in the VA health care system during the 180-day period preceding the date of separation of the member from active service.The VA-DOD Joint Executive Committee must brief Congress on the efforts to implement such a mechanism under the program.The Government Accountability Office must report on the program and include recommendations with respect to methods to improve the program.