The invention relates to a control unit for a reverse parking assistance system of a vehicle. The control unit is designed to determine a reverse travel trajectory for a reverse travel from an end position to a start position based on reference data relating to a first forward travel of the vehicle. Furthermore, the control unit is designed to control a steering device of the vehicle during the reverse travel of the vehicle as a function of the reverse travel trajectory. In addition, the control unit is designed to detect that the vehicle leaves the reverse travel trajectory on the reverse travel. Furthermore, the control unit is designed to bring about, as a reaction thereto, that in a second forward travel, the vehicle is guided to a reverse travel position, which makes it possible to guide the vehicle again along at least one section of the reverse travel trajectory to the start position.