A method for filling tanks with pressurized gas via a filling station comprising at least one source of pressurized gas and a fluid circuit for transferring the gas, comprising a first end linked to the at least one gas source and a second end provided with a transfer line intended to be removably connected to the tanks to be filled, the circuit comprising a first isolation valve, a flow or pressure regulation member, a heat exchanger for cooling the gas transferred to the tank to be filled and a second isolation valve, the method comprising successively filling a first tank then a second separate tank, characterized in that, on completion of the filling of the first tank, the first and second isolation valves are closed to trap a reserve supply of pressurized gas in the circuit between said two valves and in that the reserve supply of gas is used to fill the second tank.