Reporting Efficiently to Proper Officials in Response to Terrorism Act of 2023 or the REPORT Act of 2023 This bill requires specified federal agencies to report to Congress concerning any act of terrorism that occurs in the United States. Whenever an act of terrorism occurs, the Department of Homeland Security, the Department of Justice, the Federal Bureau of Investigation, and, as appropriate, the National Counterterrorism Center, must submit to Congress an unclassified report, which may be accompanied by a classified annex. The unclassified report shall be made available on a publicly available website. Each unclassified report and classified annex shall be made available upon request by any Member of Congress. Such report shall (1) include a statement of the facts of the act of terrorism, (2) identify any gaps in homeland or national security to prevent future acts of terrorism, and (3) include any recommendations for additional measures to improve homeland or national security. If the reporting agencies determine that any information required to be reported could jeopardize an ongoing investigation or prosecution, such agencies may withhold such information from reporting and shall notify Congress of that determination. Reports required under this bill may be combined into a quarterly report submitted to Congress. This bill shall terminate five years after its enactment.