The shadow treasurer, Chris Bowen, has conceded Labor will run larger deficits than the government over the next four years but has promised to return to surplus at the same time.

Labor has also promised significantly larger surpluses than the Coalition over 10 years, though it has not released detailed costings of its four-year and 10-year plan.

Speaking on ABC radio on Wednesday, Bowen said: “We will say, based on the government’s figures, we’d get back to budget balance in same year as the government, 2020-21.”

“Both the government and the opposition will have deficits over the forward estimates, that is true, and it is true [Labor] won’t have the same degree of fiscal contraction over the four years, but we’ll get back to budget balance in the same year.”

Labor has released its 10-year economic plan on Wednesday, the centrepiece of which is opposition to the government’s $48bn of corporate tax cuts over 10 years.

Speaking in Brisbane to release the plan, Bowen said Labor’s structural changes to the budget would allow “stronger surpluses” over 10 years than the government. Bill Shorten said Labor surpluses would “significantly outstrip” the Coalition’s in the medium term.

Labor has not released detailed costings to show how it will achieve a surplus over four years and stronger surpluses over 10 years.

Labor’s claim it can return to surplus at the same time as the government is based on the fact a number of revenue measures will ramp up towards the end of the decade, including rejecting the government’s corporate tax cuts, increasing capital gains and abolishing negative gearing for existing properties.

“The decisions we’ve taken build over time, they get implemented in our first budget then build over time to create much better structural repair to the budget.”

He called on the Coalition to release its 10-year figures, noting Labor would release both four and 10-year figures.

Bowen also took aim at the government’s prediction of a budget surplus, saying they are based on “fantasy” including optimistic growth projections and “zombie” budget measures blocked in the Senate.

On Radio National on Wednesday, the finance minister, Mathias Cormann, said Bowen had used “weasel words to hide the fact that Labor will deliver bigger deficits over the four-year budget forward estimates period”.

“Let’s see the numbers – what [Bowen has] admitted today ... is that Labor will deliver bigger deficits over the four-year budget forward estimates period and [is] asserting that somehow over the medium term they’ll be able to pay for all their unfunded spending promises.”

Cormann said the government’s four-year projections were more believable because they’d been approved in the pre-election fiscal outlook.

“Labor promising to bring the budget back into balance over an 11-year period, which is what they’re talking about when they’re talking about the medium term ... nobody can believe that based on their past performance.”

“They have a massive budget black hole and today they’re putting a lot of weasel words around fessing up that that is exactly what is happening.”

Speaking with Alan Jones on Wednesday, Malcolm Turnbull said Labor didn’t have a plan for jobs, growth or “living within our means”.

“The spendometer keeps on whirring,” he said. “We read in the papers today that Labor will produce a 10-year economic platform which is going to see debt and deficit rising over the next four years. Presumably with some better outcome 10 years from now which would be entirely speculative.”

Turnbull said: “Fairness is important ... [but] there is nothing less fair than putting up one billion dollar spending promise after another on the national credit card and leaving it our grandchildren to pay for, they don’t have a vote, they’re not voting, that’s the guts of it.”

Turnbull defended changes to the transition to retirement scheme, noting “ingenuity of the legal and accounting professions” had turned the retirement savings scheme into a tax loophole.