The Labour leader Ed Miliband has said he would use the next Budget to bring back the 10p rate of income tax, paid for by a "mansion tax" on homes worth more than £2m.
The 10p tax band was controversially scrapped by Gordon Brown.
ITV News' Political Editor Tom Bradby reports
After Ed Miliband announced that Labour will levy a 'mansion tax' on houses worth more than £2 million if they win the next election, we asked for your opinions on the ITV News Facebook page.
Jean Ballard: Why £2 million, why not houses over £500 thousand, then it includes all the MP's and well off.
Sam Greaves: I think its fair if this happens because if the poor should pay bedroom tax, the rich should pay mansion tax. However in this day and age, can we believe them?
Colin Simpson: Yes, it is right. The rich are not paying their fair share to help with the economic crisis. Some millionaires are tax evaders.
Responding to Labour's "mansion tax" announcement, the Business Secretary Vince Cable said it is "good that they've seen sense".
He said that levying a tax on houses worth more than £2 million was the "right thing to do" and that it was an "extreme anomaly" that someone living in a mansion pays the same tax as someone in a semi-detached house in the suburbs.
The Shadow Chancellor Ed Balls has said he expects a mansion tax on houses worth more than £2 million to bring in £1.7bn-£2bn.
The Prime Minister has reacted to Ed Miliband's announcement saying it looks like a policy that has been cobbled together overnight.
"I expect we will see that it is not properly costed," he added.
The Shadow Chancellor Ed Balls has admitted the then Labour Chancellor Gordon Brown was wrong to scrap the 10p tax rate.
Balls, who was a key aide to Brown, has written in the London Evening Standard:
Governments make mistakes.
But when they do it is always better to own up and put them right.
The last Labour government did many good things.
But we got things wrong too.
Scrapping the 10p tax rate, which Labour first introduced in 1999, was one of those mistakes.
The head of the CPS economic thinktank, Ryan Bourne, has tweeted that Labour's policy would not work:
Ed's numbers don't add up. Either mansion tax would have to be huge, or 10p rate tiny.From @RyanCPS on Twitter: