United States Secret Service Mission Improvement and Realignment Act of 2023 This bill transfers the U.S. Secret Service from the Department of Homeland Security to the Department of the Treasury. The bill directs the Office of Management and Budget to make incidental dispositions of personnel, assets, and liabilities held in connection with the functions transferred. The Secret Service, by December 31 of each year, shall submit to specified congressional committees an annual report on any trip by a protected individual with a stop at a location that is not owned or controlled by the federal government, including any such trip that is outside of the United States. Such report shall include (1) for each instance of such travel, a statement of the protected individuals, dates of departure and return, total amount of travel expenditures, and other specified information; and (2) for each protected individual, the total amount of incidental expenditures incurred for the purpose of providing protection to the protected individual during the reporting period.