The present invention discloses a filling device (1) for a motor vehicle operating fluid container (3). The filling device (1) comprises a mouth hole connection piece (11), into which a dispensing valve (40) can be introduced in order to fill the operating fluid container (3). The filling device (1) further comprises a compensation chamber (24) to which the mouth hole connection piece (11) is connected in fluid terms. A connection piece (21) of the filling device (1) is arranged between the operating fluid container (3) and the compensation chamber (24) and is connected in fluid terms to the operating fluid container (3) and the compensation chamber (24). The filling device (1) is distinguished in that the connection piece (21) protrudes into the compensation chamber (24), the connection piece (21) is arranged so as to face the mouth hole connection piece (11) and to be spaced apart therefrom, the connection piece (21) is surrounded by the compensation chamber (24), and a dispensing valve (40) can be introduced through the mouth hole connection piece (11) into the connection piece (21).