Former treasurer Joe Hockey is being urged not to draw from his parliamentary pension if he becomes ambassador to the United States, as a by-election date is pencilled in for his seat.

It has been reported he could be allowed to earn up to $450,000 per year if he combines his pension with his salary as an ambassador.

Mr Hockey — who is tipped to become Australia's ambassador in Washington — would earn $360,000 per year as ambassador, according to News Corp.

Under the guidelines established in 2010, Mr Hockey would also be allowed to receive up to 50 per cent of his parliamentary pension if he takes on a diplomatic posting, which would see him receive up to an additional $90,000 a year.

Independent senator Nick Xenophon has urged Mr Hockey to rule it out.

"I just want to help Joe Hockey fulfil his dream of ending the age of entitlement by Joe Hockey setting an example for the rest of us," he said.

"What Joe Hockey can do is to refuse to accept his parliamentary pension in addition to getting $330,000 a year as ambassador."

Senator Xenophon told reporters in Adelaide he would push for changes to the rules if Mr Hockey drew from his pension while he was an ambassador.

Sorry, this video has expired Xenophon calls on Hockey to avoid double dipping

"I will be putting up legislation in the Senate that will say that if an ex-politician who's getting a parliamentary pension is offered a diplomatic post, then they can't get any of that pension during that time of the diplomatic post," he said.

The Abbott government came under fire earlier this year after announcing changes to its paid parental leave policy which would stop parents "double dipping" by accessing both work and government schemes.

In a television interview, Mr Hockey said receiving payments from both schemes was "basically fraud".

Mr Hockey has long been an advocate of reducing government payments and used his valedictory speech last week to again call for an end to the "age of entitlement".

Comment is being sought from Mr Hockey.

December by-election for Hockey's seat

Mr Hockey officially resigned from Parliament last week and a by-election for his North Sydney seat is likely to be held on December 5.

While the Speaker is yet to officially declare the date, the ABC understands Prime Minister Malcolm Turnbull has signed-off on the proposal.

The Liberal Party is undergoing a pre-selection process for the blue-ribbon seat in Sydney's North Shore, with a decision to be made on Monday night.

Acting state president of the Liberal party, Trent Zimmerman, is tipped to be chosen.

The Liberal Party holds the seat with a margin of 16 per cent.