The federal government will lay out its tax and spending plans unusually early in 2019, after the budget was brought forward by a month to allow for an election in May.

Prime Minister Scott Morrison says the April 2 budget papers will finally show a surplus.

The size of the surplus will be clearer when the government’s mid-year budget review is published on December 17.

Asked about the prospect of a May election, Mr Morrison told reporters: “You do the maths … to have a half-Senate and House of Representatives election, that would have to be conducted by the 18th of May.”

“It is absolutely our intention to have the budget before the election and to deliver a surplus budget, a surplus budget that we promised to deliver.”

Treasurer Josh Frydenberg said the budget statements will distinguish between the coalition and Labor as Australians head to the polls.

“The next election will be a stark contrast,” he said.

“A contrast between a coalition government that is growing the economy and has an economic plan that is working and is for the future, and the Labor Party, who wrongly believe you can tax yourself to prosperity.”

But the treasurer also stressed a strong economy was a means to an end, rather than an end in itself.

“The benefit of a strong economy is that you can provide the essential services – the defence, the border security, the infrastructure, the disability support,” Mr Frydenberg said. “The things that Australians need and deserve.”

Neither Mr Morrison or Mr Frydenberg was worried shifting commodity prices could cause hiccups in their budget planning, because Treasury’s commodity forecasts were “very conservative”.