Child benefit withdrawal will make it better to work less for families with over seven children

And come 2076, that will be the case for every family in the nation.

The child tax credit withdrawal, taking effect on Monday, will lead to marginal tax rates of over 100 per cent on families with more than eight children earning between £50,000 and £60,000.

The IFS explains how the marginal rates are calculated:

Affected taxpayers will pay back one per cent of their family’s Child Benefit for every £100 by which taxable income exceeds £50,000. One per cent of Child Benefit is £10.56 per year for a 1-child family, and an additional £6.97 per child for larger families. Hence the marginal tax rate between £50,000 and £60,000 is increased by about 11 percentage points for the first child and by an additional 7 percentage points for each subsequent one. So, for example, while about 320,000 people will find that their marginal income tax rate increases to more than 50%, about 40,000 of them - those with three or more children - will find that it jumps to at least 65%.

They offer a chart with the rate calculated up to four children:

By seven children, the marginal rate rises to 99.35 per cent, and by eight, it breaks 100 per cent (106.32 per cent, to be exact). This means that any individual with a family of eight kids earning between £50,000 and £60,000 would be better off if they reduced their salary back down to £50,000. In fact, for that individual, they would have to earn £61,105 before their post-tax income was the same as it was at £50,000.

It's unclear whether any families actually exist matching that criterion - rather wonderfully, my back-of-the-envelope maths (which assumes that the exponential decrease in the number of families of each size continues: e.g., there are 1/8th the number of families with three or more kids as there are with two or more, so I'm assuming that there are correspondingly 1/8th the number of families with four or more as there are with three or more, and so on) suggests that there may be exactly one – but even if there are none at the moment, there's no reason why there won't be one in the future. Families with eight children do, after all, exist.

In fact, as time goes on, this problem will get worse. The IFS points out that child benefit is uprated with inflation, while tax bands aren't. Currently, each extra child after the first increases your "marginal tax rate" by around seven per cent, but suppose child benefit is uprated by two per cent a year. In that case, the marginal tax would exceed one hundred per cent for families with seven children next year; for six children in the year 2020; for five children in the year 2028; and, eventually, for families with just one child – i.e., every family – in the year 2076.

Hopefully the law will be changed before then, of course. But as a rule of thumb, laws which become ridiculously damaging unless you actively intervene ought not be signed in the first place. Oops.

Children. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

Getty Images.
Show Hide image

Jeremy Corbyn challenged by Labour MPs to sack Ken Livingstone from defence review

Former mayor of London criticised at PLP meeting over comments on 7 July bombings. 

After Jeremy Corbyn's decision to give Labour MPs a free vote over air strikes in Syria, tonight's Parliamentary Labour Party (PLP) meeting was less fractious than it could have been. But one grandee was still moved to declare that the "ferocity" of the attacks on the leader made it the most "uplifting" he had attended.

Margaret Beckett, the former foreign secretary, told the meeting: "We cannot unite the party if the leader's office is determined to divide us." Several MPs said afterwards that many of those who shared Corbyn's opposition to air strikes believed he had mishandled the process by appealing to MPs over the heads of the shadow cabinet and then to members. David Winnick declared that those who favoured military action faced a "shakedown" and deselection by Momentum activists. "It is completely unacceptable. They are a party within a party," he said of the Corbyn-aligned group. The "huge applause" for Hilary Benn, who favours intervention, far outweighed that for the leader, I'm told. 

There was also loud agreement when Jack Dromey condemned Ken Livingstone for blaming Tony Blair's invasion of Iraq for the 7 July 2005 bombings. Along with Angela Smith MP, Dromey demanded that Livingstone be sacked as the co-chair of Labour's defence review. Significantly, Benn said aftewards that he agreed with every word Dromey had said. Corbyn's office has previously said that it is up to the NEC, not the leader, whether the former London mayor holds the position. In reference to 7 July, an aide repeated Corbyn's statement that he preferred to "remember the brilliant words Ken used after 7/7". 

As on previous occasions, MPs complained that the leader failed to answer the questions that were put to him. A shadow minister told me that he "dodged" one on whether he believed the UK should end air strikes against Isis in Iraq. In reference to Syria, a Corbyn aide said afterwards that "There was significant support for the leader. There was a wide debate, with people speaking on both sides of the arguments." After David Cameron's decision to call a vote on air strikes for Wednesday, leaving only a day for debate, the number of Labour MPs backing intervention is likely to fall. One shadow minister told me that as few as 40-50 may back the government, though most expect the total to be closer to the original figure of 99. 

At the end of another remarkable day in Labour's history, a Corbyn aide concluded: "It was always going to be a bumpy ride when you have a leader who was elected by a large number outside parliament but whose support in the PLP is quite limited. There are a small number who find it hard to come to terms with that result."

George Eaton is political editor of the New Statesman.