A method for operating a brake system, which brake system includes a master brake cylinder, which is actuated by the driver with the aid of a brake force booster, a driver-independent pressure source, and at least one wheel brake to which a wheel speed sensor is assigned. During a braking operation initiated by the driver, which is identified in particular by a brake lamp switch, the present vehicle deceleration is determined and compared with a predefined threshold value, and the at least one driver-independent pressure source is activated if the determined vehicle deceleration reaches or falls below the predefined threshold value. A brake system for a motor vehicle, which brake system has a control unit in which the method is carried out is also disclosed.