Access to Congressionally Mandated Reports Act This bill requires the Government Publishing Office (GPO) to establish and maintain a publicly available website containing copies of all congressionally mandated reports. The website must feature, in addition to certain descriptive information related to such reports: (1) the ability to retrieve a report through specified types of searches; (2) a means for downloading reports individually or in bulk; (3) an electronic means for federal agencies to submit reports to the GPO, as required by the bill; and (4) in tabular form, a list of all reports that can be searched and sorted by time frame or submission status. The Office of Management and Budget must issue guidance to federal agencies on the bill's requirement for agencies to submit copies of congressionally mandated reports and related information to the GPO. With respect to each report, the relevant federal agency may redact or withhold certain information in accordance with the Freedom of Information Act and other laws. At least annually by April 1, the Library of Congress must submit to the GPO a list of all congressionally mandated reports from the previous year. The list shall be provided in an open format and must include specified identifying and otherwise descriptive information.