Joe Hockey is charging taxpayers thousands of dollars for babysitters to watch his children while he wines and dines VIPs in Washington.

Despite already collecting an estimated $360,000 salary as US ambassador - and also double-dipping into his $90,000-a-year pension - Mr Hockey billed taxpayers almost $2500 for child minding during the five months in his new role.

Documents obtained by Fairfax Media under freedom of information laws show the former federal treasurer - who once declared that the "age of entitlement" was over - is drawing on his entertainment budget five or six times a month to hire people to look after his three children.

He charges between $US50 and $140 a pop so he can have brunch with Australian government ministers, attend formal dinners and host events at his official residence.