The Prime Minister has avoided speaking to the media since the latest expenses scandal emerged in early January.
Malcolm Turnbull has now told reporters he has accepted the resignation of Health Minister Sussan Ley.
He also announced the government would introduce major changes to how politicians' use of public money is monitored.
"We are dealing with other people's money. And the Australian people are entitled to see that we are spending it wisely, appropriately, in accordance with the rules, but also in a manner that gets value for money."
The Health Minister had been under intense pressure after official government documents showed she spent thousands of dollars on travel to the Gold Coast in Queensland.
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Sussan Ley admitted on one of those trips she made what has been described as an impulse decision to buy an $800,000 apartment, but hadn't officially broken any expenses rules.
It was also revealed she claimed taxpayer-funded entitlements to travel to New Year's Eve parties, and for pilot-chartered flights on busy commercial routes when cheaper fares were available.
Ms Ley had already stood aside while her allowances claims were being investigated by the Prime Minister's department.
Malcolm Turnbull says she has made the right call to officially resign from her portfolio.
"She has made a decision, she has resigned. The important thing now is to ensure for the future that Australians are absolutely reassured that parliamentary expenses - which are work expenses after all - are appropriately spent."
In a bid to stem the impact of the expenses scandal - which is turning the spotlight on several more of his ministers - Mr Turnbull says the government will modernise the reporting of politicians' expenditure.
He's announced a new independent parliamentary expenses authority which will monitor claims by all federal politicians.
Mr Turnbull is also planning for the government to publish expenditure reports much faster.
"This will be, perhaps, the change that will have the greatest impact in the medium- and long-term. The system that manages entitlements will be modernised to allow monthly disclosure of parliamentarians' expenses in an accessible - that is to say, searchable - format."
The opposition leader Bill Shorten spoke to the Prime Minister this afternoon and gave in-principle support to the measures.
Labor and the Greens had been asking for similar changes over the past week.
