The government agreed to extend compensation to affected businesses when it responded earlier this month to a Senate inquiry into the firefighting foam contamination.

The new round of Business Hardship Payments will start on July 1, capped at $20,000 if the state government re-opens the waterways as Canberra is arguing it should.

If the state government keeps the waterway closed, affected businesses will be eligible for one-off Business Transition Payment of $25,000.

A Defence Department spokesperson confirmed the government had spent $385,380 up until April 22 on compensating people for the contamination.

The budget fine print shows the potential cost of PFOS contamination is rising, with confirmation that Airservices Australia has identified a number of sites around Australia that are potentially contaminated with polyflourinated chemicals (PFCs) from firefighting foams, which it says were widely used at Australian airports from 1980 until 2010.

Testing for the chemicals at unnamed sites began in 2008-09.

"The amount for potential long-term remediation costs cannot be quantified at this time,'' Budget Paper No1 says.

In line with recent years, the budget contained substantial funding commitments to RAAF Williamtown.

The base will receive at least $360 million in major capital works this year as it prepares to host Australia's next generation war plane, the Joint Strike Fighter.

The Williamtown funds are about the only Hunter-specific measures in a federal budget that had little in the way of surprises after its four biggest initiatives - a tobacco excise increase, a lift in the cut-off for $80,000 to $87,000, a "Google" tax to lessen offshore tax avoidance and an extension of the 2015 "Tony's tradies" small business deduction regime - were leaked in the lead-up to Tuesday night's budget speech by Treasurer Scott Morrison.

The budget deficit this financial year is $39.9 billion, falling to $37.1 billion in 2016-17. The deficit is predicted to fall to just $6 billion in 2019-20 but economists are widely questioning this as an outcome, given the risks to growth from global financial instability.

Mr Morrison said the government was "living within its means", while using the tax system to encourage jobs and growth, while cracking down on tax avoidance and "generous tax concessions for Australia's most wealthy".

At the same time, the government would "cut unnecessary waste" and "target welfare abuse to protect our social safety net" for "Australia's most vulnerable, in particular those with disabilities".

The budget shows that the National Disability Insurance Scheme, trialled in Newcastle since 2013, is facing a funding shortfall of more than $4 billion a year by 2019-20, even with the related 0.5 per cent rise in the Medicare levy introduced to fund the scheme.

The government is seeking savings in other parts of the welfare budget to pay for the NDIS.