Shut-off device for a gas tank apparatus, comprising a first connector for connection to a high-pressure tank and a second connector for connection to a supply line, a main valve chamber, which has a first opening connected to the first connector in a fluidically conductive manner, a second opening connected to the second connector in a fluidically conductive manner, and a first control opening, and a main valve, which is designed as a switchable solenoid valve and has a main valve needle arranged in the main valve chamber, which can be moved between a closed position, in which it bears against a main valve seat surrounding the second opening in order to seal the second opening with respect to the first opening, and an open position, in which it is lifted from the main valve seat, wherein the main valve needle divides the main valve chamber into an outlet chamber, into which the first and the second opening (21, 22) open, and a control chamber, into which the first control opening opens and which is connected to the outlet chamber in a fluidically conductive manner, wherein the shut-off device has a servo valve chamber spatially separated from the main valve chamber, which comprises a second control opening connected to the first control opening in a fluidically conductive manner and a servo opening connected to the second connector in a fluidically conductive manner, characterized in that the shut-off device has a servo valve, which is designed as a switchable solenoid valve, having a servo valve needle arranged in the servo valve chamber, which can be moved between a closed position, in which it bears against a servo valve seat surrounding the servo opening in order to seal the servo opening with respect to the second control opening, and an open position, in which it is lifted from the servo valve seat. and a main valve, which is designed as a switchable solenoid valve and has a main valve needle arranged in the main valve chamber, which can be moved between a closed position, in which it bears against a main valve seat surrounding the second opening in order to seal the second opening with respect to the first opening, and an open position, in which it is lifted from the main valve seat, wherein the main valve needle divides the main valve chamber into an outlet chamber, into which the first and the second opening (21, 22) open, and a control chamber, into which the first control opening opens and which is connected to the outlet chamber in a fluidically conductive manner, wherein the shut-off device has a servo valve chamber spatially separated from the main valve chamber, which comprises a second control opening connected to the first control opening in a fluidically conductive manner and a servo opening connected to the second connector in a fluidically conductive manner, characterized in that the shut-off device has a servo valve, which is designed as a switchable solenoid valve, having a servo valve needle arranged in the servo valve chamber, which can be moved between a closed position, in which it bears against a servo valve seat surrounding the servo opening in order to seal the servo opening with respect to the second control opening, and an open position, in which it is lifted from the servo valve seat.