Ed Miliband said Labour would reverse the coalition's cut in the top rate of tax from 50p to 45p "if there was an election tomorrow".
"Next April David Cameron will be writing a cheque to each and every millionaire in Britain for £40,000," he told BBC's Andrew Marr show.
"If I was in government tomorrow one change I would make in relation to the better off - first change in a Labour budget - we wouldn't be cutting the top rate of income tax from 50 to 45p.
"If there was an election tomorrow that is what we would do."
Ed Miliband told BBC's Andrew Marr show that a Labour government would repeal NHS reforms.
"We will repeal [the Coalition's] NHS bill. Why? Because it put the wrong principles back at the hart of the NHS," he said.
Ed Miliband told BBC's Andrew Marr show that a Labour government would still make cuts but at a slower pace to the Coalition's strategy:
"Yes, there would be cuts if we were in government, but actually if you make the pace of those cuts slower, if you take less money out of the economy now...it would be better for getting the deficit down sustainably."
Labour leader Ed Miliband told BBC's Andrew Marr show that he doesn't want to be seen as a party that represents only union interests.
"I'm not for pushing people out of the Labour party - I want more people in the Labour party, and there's no future for this party as a party of one sectional interest of society," he said.
"We must be the party of the private sector just as much as the party of the public sector."
A Labour Party spokesman said:
Under Ed Miliband's leadership we are a united party, speaking for the whole country and the change that Britain needs from this Tory-led Government.
When the country is in recession and the deficit is rising so far this year under Cameron and Osborne it would not be responsible for Labour to make promises we don't know we can keep.
- 1400: Conference opens.
- Session on "rebuilding the economy" including shadow business secretary Chuka Umunna.
- Session on "rebuilding our party" including general secretary Iain McNicol, chairwoman of the national policy forum Angela Eagle, policy review co-ordinator Jon Cruddas and deputy chairman Tom Watson.
- 1730: End of session.
Ed Balls also dismissed suggestions that he is a bully in the Sunday Telegraph interview, saying he hoped his shadow cabinet colleagues saw him as "supportive and nurturing".
He denied reported fiction between him and Ed Miliband risked turning into a repeat of the damaging Blair-Brown battles.
"If there were ever any issues, then Ed and I, as we have done for 20 years, we sit down and talk it through, and we work it out," Mr Balls said.
"We don't do it through intermediaries, and we don't do it through the newspapers, and we don't do it through argument or dispute," he added.
Shadow Chancellor Ed Balls has attempted to ramp pressure on George Osborne with a call for a two-year stamp duty holiday for first-time buyers.
Chancellor Osborne is under pressure from the right of his party to cut taxes.
Mr Balls said he could not yet promise to reverse any coalition spending cuts.
But he told the Sunday Telegraph that suspending the levy on properties worth less than £250,000 would help revive the housing market and the general economy.
Mr Balls is expected to explain how it could be afforded in his conference speech later today in Manchester.
Ed Miliband's threat to break up Britain's biggest banks comes in the wake of the Libor-fixing scandal and further revelations of mis-selling by the high street giants.
Under government plans, banks have until 2019 to ring-fence high street operations handling consumer and small business accounts from high-risk "casino" arms within the same group.
But Labour has said the Coalition are moving too slowly to force change, while accusing Chancellor George Osborne of watering down the reforms called for in the Vickers review in the face of lobbying by the industry.
Mr Miliband said a Labour administration would legislate if major changes were not in place by the 2015 General Election.
The party wants to see evidence of a cultural change and the Vickers report implemented in "letter and spirit", including splitting staffing and corporate governance.
Labour goes into its party conference 10 points ahead of the Conservatives, according to a poll by Opinium/Observer.
Labour is on 39%, while the Conservatives are on 29% and the Liberal Democrats on 10%.