"Brown's mistake" has already been reversed

The personal allowance has grown to undo any losses the abolition of the 10p rate inflicted.

Brown walks through Rugby. Photograph: Getty Images

Ed Miliband has committed to introducing a mansion tax, and using the money to fund a re-introduction of the 10p tax band, saying:

We would tax houses worth over £2 million. And we would use the money to cut taxes for working people. We would put right a mistake made by Gordon Brown and the last Labour government. We would use the money raised by a mansion tax to reintroduce a lower 10 pence starting rate of tax, with the size of the band depending on the amount raised. This would benefit 25 million basic rate taxpayers.

The original 10 pence tax band was applied on incomes between £0 and £2,230, once the personal allowance was taken into account. Its abolition was used to fund the reduction in the basic rate of tax from 22p to 20p. But while Miliband says he will "put right [the] mistake made by Gordon Brown", he's not going to be reversing the basic rate cut. Instead, the money will come from the mansion tax.

But the Social Market Foundation's Ian Mulheirn points out that that mansion tax is not expected to raise anywhere near as much as two per cent on the basic rate of tax would. He tells me that their expectation for a mansion tax on houses over £2m is in the low billions — probably around £2bn or £3bn.

But every billion pounds raised would only pay for a 10p tax band of between two and three hundred pounds, he says:

We've got about 30 million income taxpayers in the UK, once you take the personal allowance into account. Assuming that they all would benefit by the full amount, then if you've got £1bn to play with, you could have a tax band of about £330.

A tax band of £330 would return £33 to each taxpayer. If the mansion tax raises the high end of estimates, then the band could be around £1000, returning £100 to each taxpayer. That's not to be sniffed at, but it's less than half of the size of the abolished band. It's not putting right Brown's mistake, but it ameliorates it slightly.

But actually, Brown's mistake has already been largely put right.

In 2007, the last year of the 10p tax rate, the personal allowance stood at £5,035. With the 10p band on top, basic rate tax started at £7,265. Uprated for inflation, that will be worth slightly under £9000 in the tax year starting in 2013.

In that same year, the personal allowance will stand at £9,440. Someone who would in 2007 have been paying only the 10p tax rate is today paying no tax at all. Miliband's actions, if introduced in 2015, will likely introduce a reduced tax rate for people earning between £10,000 and £11,000 to complement a zero tax rate for people earning less than that. That's likely a good thing; but it's a new thing, not a reversal of Brown's actions. They have already been undone.

Of course, if you have to delve into uprating tax bands by inflation to prove a point, it's not going to fly very well in political debates. That's why, as George writes, politically, the move is a masterstroke.