While a significant proportion of the spending hikes of the past two years are a consequence of Senate resistance to the 2014 budget, a quick look at the evolution of payment decisions shows the Turnbull government continues to struggle with one of its primary goals - keeping a lid on the size of government.

The mid-year budget update just before Christmas involved an extra $3.6 billion in spending decisions, around a third of which was for additional regional roads funding.

Another $909 million was earmarked for the resettlement of an extra 12,000 Syrian refugees, with significant spending increases for counter-terrorisism, security at Parliament House, immigration cases, science and innovation, and the war in Syria.

Some of the biggest spending hits were caused by the reversal of major elements of the 2014 budget.

Spending increases since the 2014 budget

The biggest was a $2.9 billion bill over five years for the government's decision to scrap the Medicare co-payment at the heart of the 2014 budget, followed by $1.8 billion was for reversing the 2014 plan to force dole-seekers under 30 to wait six months for their payments.

The government blames the Senate for blocking those measures and was forced to spend $6.6 billion on a range compensation measures that had previously been funded by the mining tax, which the Coalition succeeded in dumping with the support of Senate cross-benchers.

The deal with the cross-benchers saved $10 billion, but fell short of the original $16 billion in compensation measures, which included the school kids' bonus,


Constant announcement of additional spending measures - with 13 major ones detailed in budget and mid-year updates since late 2014 - highlights the ongoing need for broader budget restraint if the Coalition is to successfully keep payments as a proportion of the economy below 26 per cent.

Natural disasters, unexpected wars or humanitarian crises, social welfare issues and infrastructure needs will almost certainly force the government to add new spending items in coming years.

At the same time, the Coalition faces considerable political pressure to do something about so-called bracket-creep, which will see an ever-rising number of Australian workers paying the second-highest tax rate because of wage gains.

"The pressures on the budget going forward are increasing," Mr Morrison said. "There will be new asks for new spends. These are the areas where we need to look for different answers rather than just asking the taxpayer to stump up."