In a no-losers budget just weeks out from the May election, Treasurer Josh Frydenberg pitched the coalition as responsible economic managers who can still splash some cash.

Infrastructure funding will jump $25 billion to $100 billion over the next 10 years in a bid to connect Australia's job-creating cities with regional population centres.

Mr Frydenberg's first budget also predicts surpluses from next financial year, starting with $7.1 billion in 2019/20.

"The budget is back in the black and Australia is back on track," Mr Frydenberg said on Tuesday night.

Last year's $530 tax offset for low- and middle-income earners has been doubled to $1080 for more than 10 million taxpayers earning up to $126,000 a year.

About 4.5 million Australian workers will get the full amount, starting from next year's tax returns, should the coalition government be returned.

In 2024, the 32.5 per cent tax rate will drop to 30 per cent, meaning workers earning from $45,000 to $200,000 will pay 30 cents in every dollar.

"We will put a speed limit on taxes, while our opponents will put a speed limit on the economy," Mr Frydenberg said.

But the coalition will not attempt to get the tax cuts through parliament before the election.

The budget's wage growth predictions remain high at 3.25 per cent from 2020 onwards, but other forecasts are more conservative.

Mr Frydenberg expects employment growth to drop to 1.75 per cent for the next two years, while the unemployment rate is tipped to remain static at five per cent over the next four years.

To build $100 billion worth of infrastructure projects over the next decade, $525 million will be spent to create an extra 80,000 new apprenticeships in industries with skills shortages.

Bakers, carpenters, plumbers and others will get $8000 for taking on an apprentice, while the apprentices themselves will get $2000.

"There will be cranes, there will be hard hats, there will be heavy machinery across the country," Mr Frydenberg said.

The small business instant asset write-off has been increased to $30,000, and the definition has been increased to include businesses with turnover below $50 million a year.

The coalition has avoided touching the three areas Labor is promising to hit if it wins the May election - negative gearing, trusts, and dividend imputation.

"We are not increasing taxes, the Labor party is, that is the clear contest between now and the next election," the treasurer said.

Mr Frydenberg promised to erase Australia's $373 billion of net debt by 2030, starting with a $12 billion reduction in 2019/20.

"We are reducing the debt and this interest bill. Not through higher taxes, but by responsible budget management and by growing the economy," he said.

Australian Associated Press