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.

Photo: Getty
Show Hide image

Who will win in Stoke-on-Trent?

Labour are the favourites, but they could fall victim to a shock in the Midlands constituency.  

The resignation of Tristram Hunt as MP for Stoke-on-Central has triggered a by-election in the safe Labour seat of Stoke on Trent Central. That had Westminster speculating about the possibility of a victory for Ukip, which only intensified once Paul Nuttall, the party’s leader, was installed as the candidate.

If Nuttall’s message that the Labour Party has lost touch with its small-town and post-industrial heartlands is going to pay dividends at the ballot box, there can hardly be a better set of circumstances than this: the sitting MP has quit to take up a well-paid job in London, and although  the overwhelming majority of Labour MPs voted to block Brexit, the well-advertised divisions in that party over the vote should help Ukip.

But Labour started with a solid lead – it is always more useful to talk about percentages, not raw vote totals – of 16 points in 2015, with the two parties of the right effectively tied in second and third place. Just 33 votes separated Ukip in second from the third-placed Conservatives.

There was a possible – but narrow – path to victory for Ukip that involved swallowing up the Conservative vote, while Labour shed votes in three directions: to the Liberal Democrats, to Ukip, and to abstention.

But as I wrote at the start of the contest, Ukip were, in my view, overwritten in their chances of winning the seat. We talk a lot about Labour’s problem appealing to “aspirational” voters in Westminster, but less covered, and equally important, is Ukip’s aspiration problem.

For some people, a vote for Ukip is effectively a declaration that you live in a dump. You can have an interesting debate about whether it was particularly sympathetic of Ken Clarke to brand that party’s voters as “elderly male people who have had disappointing lives”, but that view is not just confined to pro-European Conservatives. A great number of people, in Stoke and elsewhere, who are sympathetic to Ukip’s positions on immigration, international development and the European Union also think that voting Ukip is for losers.

That always made making inroads into the Conservative vote harder than it looks. At the risk of looking very, very foolish in six days time, I found it difficult to imagine why Tory voters in Hanley would take the risk of voting Ukip. As I wrote when Nuttall announced his candidacy, the Conservatives were, in my view, a bigger threat to Labour than Ukip.

Under Theresa May, almost every move the party has made has been designed around making inroads into the Ukip vote and that part of the Labour vote that is sympathetic to Ukip. If the polls are to be believed, she’s succeeding nationally, though even on current polling, the Conservatives wouldn’t have enough to take Stoke on Trent Central.

Now Theresa May has made a visit to the constituency. Well, seeing as the government has a comfortable majority in the House of Commons, it’s not as if the Prime Minister needs to find time to visit the seat, particularly when there is another, easier battle down the road in the shape of the West Midlands mayoral election.

But one thing is certain: the Conservatives wouldn’t be sending May down if they thought that they were going to do worse than they did in 2015.

Parties can be wrong of course. The Conservatives knew that they had found a vulnerable spot in the last election as far as a Labour deal with the SNP was concerned. They thought that vulnerable spot was worth 15 to 20 seats. They gained 27 from the Liberal Democrats and a further eight from Labour.  Labour knew they would underperform public expectations and thought they’d end up with around 260 to 280 seats. They ended up with 232.

Nevertheless, Theresa May wouldn’t be coming down to Stoke if CCHQ thought that four days later, her party was going to finish fourth. And if the Conservatives don’t collapse, anyone betting on Ukip is liable to lose their shirt. 

Stephen Bush is special correspondent at the New Statesman. His daily briefing, Morning Call, provides a quick and essential guide to British politics.