Optimal tax rate for top one per cent may be as high as 83%

Paper suggests cutting taxes may divert attention to wasteful bargaining

Via Daniel Elton, a new(ish) paper (pdf) by economists Thomas Piketty, Emmanuel Saez and Stefanie Stantcheva makes the case for the optimal tax rate of the richest one per cent could be as high as 83 per cent.

The authors look at three possible ways in which top incomes respond to marginal tax rates.

The first is the "supply side" channel cited by Arthur Laffer when he developed his concept of the Laffer curve. Under this channel, marginal tax rates that are too high result in people doing less work than they otherwise would. Lower tax rates thus respond to more economic activity, and greater growth and higher tax revenue. Laffer's work was used by the Reagan administration to justify cutting the top rate in the US, from 70 per cent down to 28 per cent.

The second is the "tax avoidance" channel. This is the model cited by the Chancellor when he made the decision to cut the tax rate for top earners in Britain from 50 per cent to 45 per cent. The argument is that high tax rates increase tax avoidance, but the authors argue – in common with many of the Chancellors critics – that tax avoidance can be dealt with directly, writing that:

A better policy would be to first close loopholes so as to eliminate most tax avoidance opportunities and only then increase top tax rates.

The third is the "compensation bargaining" channel. The authors argue that:

While standard economic models assume that pay reflects productivity, there are strong reasons to be sceptical, especially at the top of the income distribution where the actual economic contribution of managers working in complex organisations is particularly difficult to measure.

As a result, top workers have ample opportunity to set their own pay, through bargaining harder or influencing compensation committees. The incentives for this economically wasteful activity are higher the lower tax rates are. Just as with the supply side model, tax cuts increase the wealth of the richest in society, but unlike that model they do not also increase growth; rather, the extra money for the rich comes from those poorer than them.

The authors, using their estimates of the elasticity of the various channels (that is, the magnitude of the effect), then calculate what the optimum rates would be. Under the first model, they find it to be roughly 57 per cent – 5 per cent higher than the top British tax rate is until the cut takes effect (National Insurance for top earners is 2per cent). Assessing the second model (Osborne's preferred argument), they find that the optimal tax rate would be 62 per cent, but argue that if the correct anti-avoidance and simplification measures were put in place, it would be 71 per cent.

The third model, however, outputs an optimal rate of 83 per cent. The authors still assume a minor supply-side effect, making up 40 per cent of the total elasticity, which is why it isn't higher. That is, they still assume that high tax rates will encourage the rich to work less, but they also assume that they will encourage the rich to put more of their effort into actual work, and less of it into "compensation bargaining".

How to decide between models one and three (the authors assume that once anti-avoidance measures are put in place, model two is the same as model one)? The former predicts that lower tax leads to more work, the latter that it merely leads to higher pay. As a result, tax cuts should be correlated with higher growth. Are they? Well, no:

As a result, the bargaining model can at least be said to be as realistic as the supply-side model; and if that's the case, the optimal top tax rate for most nations is likely to be far in excess of where it is set now.

For more, see the authors in the Boston Review, VoxEU, or their original paper (pdf).

Pictured: Laffer. No, wait, laughers. 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.

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How the row over Jackie Walker triggered a full-blown war in Momentum

Jon Lansman, the organisation's founder, is coming under attack. 

The battle for control within Momentum, which has been brewing for some time, has begun in earnest.

In a sign of the growing unrest within the organisation – established as the continuation of Jeremy Corbyn’s first successful leadership bid, and instrumental in delivering in his re-election -  a critical pamphlet by the Alliance for Workers’ Liberty (AWL), a Trotskyite grouping, has made its way into the pages of the Times, with the “unelected” chiefs of Momentum slated for turning the organisation into a “bland blur”.

The issue of contention: between those who see Momentum as an organisation to engage new members of the Labour party, who have been motivated by Jeremy Corbyn but are not yet Corbynites.

One trade unionist from that tendency described what they see the problem as like this: “you have people who have joined to vote for Jeremy, they’re going to meetings, but they’re voting for the Progress candidates in selections, they’re voting for Eddie Izzard [who stood as an independent but Corbynsceptic candidate] in the NEC”.  

On the other are those who see a fightback by Labour’s right and centre as inevitable, and who are trying to actively create a party within a party for what they see as an inevitable purge. One activist of that opinion wryly described Momentum as “Noah’s Ark”.

For both sides, Momentum, now financially stable thanks to its membership, which now stands at over 20,000, is a great prize. And in the firing line for those who want to turn Momentum into a parallel line is Jon Lansman, the organisation’s founder.

Lansman, who came into politics as an aide to Tony Benn, is a figure of suspicion on parts of the broad left due to his decades-long commitment to the Labour party. His major opposition within Momentum and on its ruling executive comes from the AWL.

The removal of Jackie Walker as a vice-chair of Momentum after she said that Holocaust Memorial Day belittled victims of other genocides has boosted the AWL, although the AWL's Jill Mountford, who sits on Momentum's ruling executive, voted to remove Walker as vice-chair. (Walker remains on the NEC, as she has been elected by members). But despite that, the AWL, who have been critical of the process whereby Walker lost her post, have felt the benefit across the country.

Why? Because that battle has triggered a series of serious splits, not only in Momentum’s executive but its grassroots. A raft of local groups have thrown out the local leadership, mostly veterans of Corbyn’s campaign for the leadership, for what the friend of one defeated representative described as “people who believe the Canary [a pro-Corbyn politics website that is regularly accused of indulging and promoting conspiracy theories]”.

In a further series of reverses for the Lansmanite caucus, the North West, a Momentum stronghold since the organisation was founded just under a year ago, is slipping away from old allies of Lansman and towards the “new” left. As one insider put it, the transition is from longstanding members towards people who had been kicked out in the late 1980s and early 1990s by Neil Kinnock. The constituency party of Wallasey in particular is giving senior figures in Momentum headaches just as it is their opponents on the right of the party, with one lamenting that they have “lost control” of the group.

It now means that planned changes to Momentum’s structure, which the leadership had hoped to be rubberstamped by members, now face a fraught path to passage.

Adding to the organisation’s difficulties is the expected capture of James Schneider by the leader’s office. Schneider, who appears widely on television and radio as the public face of Momentum and is well-liked by journalists, has an offer on the table to join Jeremy Corbyn’s team at Westminster as a junior to Seumas Milne.

The move, while a coup for Corbyn, is one that Momentum – and some of Corbyn’s allies in the trade union movement – are keen to resist. Taking a job in the leader’s office would reduce still further the numbers of TV-friendly loyalists who can go on the airwaves and defend the leadership. There is frustration among the leader’s office that as well as Diane Abbott and John McDonnell, who are both considered to be both polished media performers and loyalists, TV bookers turn to Ken Livingstone, who is retired and unreliable, and Paul Mason, about whom opinions are divided within Momentum. Some regard Mason as a box office performer who needs a bigger role, others as a liability.

But all are agreed that Schneider’s expected departure will weaken the media presence of Corbyn loyalists and also damage Momentum. Schneider has spent much of his time not wrangling journalists but mediating in local branches and is regarded as instrumental in the places “where Momentum is working well” in the words of one trade unionist. (Cornwall is regarded as a particular example of what the organisation should be aiming towards)

It comes at a time when Momentum’s leadership is keen to focus both on its external campaigns but the struggle for control in the Labour party. Although Corbyn has never been stronger within the party, no Corbynite candidate has yet prevailed in a by-election, with the lack of available candidates at a council level regarded as part of the problem. Councilors face mandatory reselection as a matter of course, and the hope is that a bumper crop of pro-Corbyn local politicians will go on to form the bulk of the talent pool for vacant seats in future by-elections and in marginal seats at the general election.

But at present, a draining internal battle is sapping Momentum of much of its vitality. But Lansman retains two trump cards. The first is that as well as being the founder of the organisation, he is its de facto owner: the data from Jeremy Corbyn’s leadership campaigns, without which much of the organisation could not properly run, is owned by a limited company of which he is sole director. But “rolling it up and starting again” is very much the nuclear option, that would further delay the left’s hopes of consolidating its power base in the party.

The second trump card, however, is the tribalism of many of the key players at a local level, who will resist infiltration by groups to Labour’s left just as fiercely as many on the right. As one veteran of both Corbyn’s campaigns reflected: “If those who have spent 20 years attacking our party think they have waiting allies in the left of Labour, they are woefully mistaken”. 

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