Finance Minister Mathias Cormann booked flights costing $37,000 so he could spruik the Government's personal tax cuts and lobby crossbenchers for its corporate tax plan.

Key points: Mathias Cormann was the sole passenger on the flight from Canberra to Perth, via Adelaide

Mathias Cormann was the sole passenger on the flight from Canberra to Perth, via Adelaide The Minister went to South Australia to lobby crossbenchers on a now-abandoned corporate tax plan

The Minister went to South Australia to lobby crossbenchers on a now-abandoned corporate tax plan His office argues it was within the rules, which require consideration of value for public money

On June 22 — the day after the Parliament agreed to personal tax cuts last year — Senator Cormann made a choice to perform media duties in Canberra in the morning then visit Adelaide on the way back to Perth.

No commercial flights were available to meet these requirements, so he booked flights on a CL604 Challenger defence jet, attracting a cost 20 times the price of the ticket he would use to get back to Canberra two days later.

A spokesperson for Senator Cormann said "use of the special purpose aircraft was approved in the appropriate way to facilitate official business in Adelaide in transit from Canberra back to Perth in between two parliamentary sitting weeks".

Government needed support for corporate tax breaks

The $37,000 cost is made up of fuel, landing fees and airport handling charges for the flights to Adelaide, then on to Perth, as well as the plane's return to Canberra.

A spokesperson for Minister for Defence Christopher Pyne, who is responsible for the aircraft, said "when considering the use of [Special Purpose Aircraft] to enable ministers to adequately perform their duties, consideration is given to the availability and suitability of commercial travel".

"In circumstances where commercial alternatives are readily available, the most efficient means of transport will be utilised and the [Special Purpose Aircraft] may not be used," the spokesman said.

The law governing the scheme requires the minister for defence to "not approve a use of special purpose aircraft that would not provide value for money in the circumstances, taking into account the need to conduct the relevant member's parliamentary business".

At the time, the Government needed support from the Senate for its business tax plan, which has since been abandoned.

That plan would have reduced the tax rate for large companies from 30 per cent to 25 per cent.

The $37,000 cost to use the plane, a CL604 Challenger defence jet, included fuel, landing fees and handling charges. ( Royal Australian Air Force, file photo )

The ABC has confirmed Senator Cormann met with Centre Alliance senators Stirling Griff and Rex Patrick in Adelaide, but he did not meet with South Australian independent senator Tim Storer. All were opposed to the corporate tax plan.

Senator Griff said there was benefit in having a face-to-face meeting, but there was no urgency in this case given they would see each other in Parliament three days later.

"It wasn't a meeting we instigated, it was a meeting that the Minister wanted to have with us to just discuss upcoming legislation," he said.

"Look, it could have happened that day, it could have happened the next day, it could have happened three or four days later.

"I don't believe at the time there was a critical need for a meeting on that day."

Senator Cormann's office would not reveal details of any meetings or functions he attended in Adelaide.

MPs need to justify aircraft usage post 'Choppergate'

The entitlements system for politicians was overhauled in the wake of Bronwyn Bishop's "Choppergate" scandal, and MPs now must be prepared to publicly justify their use of public resources.

Senator Cormann typically flies commercial between Perth and Canberra, at a cost of between $1,500 and $3,000.

He flew back to Canberra from Perth that Sunday, June 24, on a commercial flight at a cost of $1,808.

He has flown to and from Perth previously on a defence jet, but is commonly accompanied by staff or parliamentary colleagues.

Mr Pyne has previously argued that it may be more efficient to use the defence aircraft in cases where there are multiple passengers.

Of the 193 requests for special purpose aircraft in the first half of 2018, only Senator Cormann's booking for June 22 involved a single passenger.

The CL604 Challenger is part of the Air Force fleet and when flies is staffed by three crew. ( Department of Defence: LAC Aaron Curran )

Senator Cormann has risen to become a senior member of the Coalition since entering Parliament in 2007.

He abandoned support for Malcolm Turnbull during the week of the Liberal leadership spill in August, leading to the removal of the prime minister.