Securely Expediting Clearances Through Reporting Transparency Act of 2018 or the SECRET Act of 2018 (Sec. 3) This bill requires the National Background Investigations Bureau (NBIB) within the Office of Personnel Management (OPM) to report on its backlog of security clearance investigations. The report must include a backlog mitigation plan identifying the cause of, and making recommendations to remedy, the backlog. (Sec. 4) The Executive Office of the President must report on the process for conducting and adjudicating security clearance investigations for the President's staff. (Sec. 5) The OPM must report on the costs of maintaining comprehensive background investigations capability within both the NBIB and the Department of Defense, compared to the costs of sustaining a single government-wide background investigations enterprise. (Sec. 6) The Office of the Director of National Intelligence (ODNI) must report on: (1) the status of implementing government-wide continuous evaluation programs, (2) efforts by federal agencies to meet requirements for reciprocal recognition to access classified information, and (3) whether the schedule for processing security clearances should be modified. (Sec. 7) The ODNI and the OPM must review and make recommendations to Congress and the President, as appropriate, to issue guidance to assist agencies in determining: (1) position sensitivity designation, and (2) the appropriate background investigation to initiate for each position designation. The President must report on any issues identified in, and the number of position designations revised as a result of, the review.