Secret Service Recruitment and Retention Act of 2018 (Sec. 2) This bill amends the Overtime Pay for Protective Services Act of 2016 to extend through 2018, subject to specified limitations, the exemption of U.S. Secret Service officers, employees, and agents who perform protective services from the limitation on premium pay otherwise applicable to federal employees. The bill specifies that the exemption also applies to the U.S. Secret Service Uniformed Division. The bill provides that such amendments shall take effect as if they had been enacted on December 31, 2016. The Secret Service must report to Congress by January 30, 2018, and January 30, 2019, on premium pay above the limitation paid to Secret Service personnel in the previous year. (Sec. 3) The Government Accountability Office shall study and report to specified congressional committees on the extent of the progress made by the Secret Service in implementing the recommendations of the U.S. Secret Service Protective Mission Panel, including those items which pertain to training and personnel enumerated in the Executive Summary to Report from the panel to the Secretary of Homeland Security, dated December 15, 2014.