Abstract: An assembly is for filling a gas tank for a combustion engine from a gas-filled storage bottle via a filling device arranged between the tank and the storage bottle. The tank has at least one fill valve for liquefied gas, a pressure relief valve for gas in the gaseous state, and an extraction valve for liquefied gas. The filling device has a gas connection for the storage bottle and has a fill connection for the fill valve. For filling the tank, the fill valve is connected via the filling device to the storage bottle, such that, when the fill valve is open, liquefied gas flows from the storage bottle via the fill valve into the tank. During the inflow of liquefied gas, the pressure relief valve of the tank is at least intermittently open. A filling level gauge is provided for indicating a predefined filling level in the tank.