Labour will balance the UK's books and deliver a budget surplus in the next Parliament if it wins the 2015 election, Ed Balls has said.
The shadow chancellor said Labour would pass a law to ensure it adheres to "tough" and binding fiscal rules.
This would mean eliminating the deficit - so the government generates more cash than it spends - and cutting debt as a share of GDP between 2015 and 2020.
George Osborne says the Tories want an absolute budget surplus by 2020.
The last time the government ran an absolute budget surplus - which means generating more in revenues, including tax yields, than the entire expenditure - was in 2001.
Labour's ambition to deliver a budget surplus does not include borrowing additional money for long-term investments, such as a high speed rail link.
The Labour party is under pressure to assert its economic credibility in the face of claims from its rivals that it would increase spending and borrowing.
In a speech to the Fabian Society on Saturday, Mr Balls said a future Labour government would legislate within the first year to introduce new rules on the deficit and debt levels while progress would be independently audited by the Office for Budget Responsibility.
But he would not set a specific date for achieving a surplus, saying it would depend on the state of the public finances and changing economic circumstances.
"The next Labour government will balance the books and deliver a surplus on the current budget and falling national debt in the next Parliament," he said.
"We will get the current budget into surplus as soon as possible in the next Parliament. How fast we can go will depend on the state of the economy and public finances we inherit."
A Conservative spokesman said: "Labour spent too much in the good years, left behind the biggest deficit in the developed world, and even deny leaving our economy in a mess in the first place - and now Ed Miliband and Ed Balls are saying we aren't clearing up their mess fast enough.
"As part of our long-term economic plan, we're taking difficult decisions to reduce the deficit to secure a better future for Britain.
"Already it is down by a third, keeping mortgage rates low - bringing more financial security and peace of mind for people who work hard."
In his recent Autumn Statement Mr Osborne said he expected the UK to be running a budget surplus by financial year 2018-19.
Economists have said this could lead to further substantial cuts to public spending - although Prime Minister David Cameron said spending could instead be frozen.
He has said if the economy grows it could even be possible to spend more on some departments and run a surplus.
Labour has already pledged to stick to the government's spending plans for the first year after the general election.
"No more borrowing for current spending under Labour," Mr Balls said in December. "There'll be spending cuts, there'll be tough decisions."