Prime Minister Tony Abbott says the Speaker of the House of Representatives cannot afford any future "errors".

Mr Abbott's warning to Bronwyn Bishop comes after much scrutiny following her decision to charge taxpayers for a short helicopter ride to a political fundraiser.

On Monday, Mr Abbott said Mrs Bishop was "on probation" over her decision to charter a helicopter to get to Liberal function at a Victorian golf course near Geelong.

The term has been lampooned by the Manager of Opposition Business Tony Burke, who held up a P plate at his media conference on Tuesday.

On Tuesday, Mr Abbott told reporters Mrs Bishop has his confidence but he does not want to "minimise" her serious error of judgement.

"The message to Bronwyn — the message to all of us — is please no errors in the future like the sorts of errors we have seen in the not-too-distant past," Mr Abbott said.

But Mr Abbott's explanation failed to satisfy Opposition Leader Bill Shorten.

"How long does probation go for? Is there any docking of her pay?" Mr Shorten said.

"Does Mr Abbott really think that we need to have the Speaker of the Parliament with training wheels on?

"What's the consequences of infringing probation?"

'Does not pass the pub test'

Independent senators John Madigan and Nick Xenophon will try to amend the rules governing politicians' entitlements when Parliament resumes.

Independent senator John Madigan protests against large entitlement spending by members of parliament. ( ABC News )

Senator Madigan says the current guidelines are too vague.

"I myself on numerous occasions, having sought clarification from the office who deals with entitlements, has found that even they're vague on what is acceptable or not acceptable and often refer you to your own accountant to get clarification," he said.

"Now how on earth your accountant is supposed to make head nor tail of this if they can't is beyond me.

"The whole system needs a major overhaul. The current system does not pass the average punters' pub test."