It's a shame that the publishers chose not to replicate the green ink in which this book was clearly written. And rather tempting to misquote a quote, itself misattributed to Samuel Johnson: "The policy prescriptions in this book are stimulating and sensible. But what is stimulating is not sensible: what is sensible is not stimulating."
Murphy has many sensible things to say about what a tax system is designed to achieve. But I don't think his principles are as contentious as he himself seems to think. What is contentious is the ability to implement them in a large, complex, open and largely private economy, where one isn't starting with a blank sheet of paper - a practical issue that he acknowledges but doesn't proceed to solve. And as I will mention below there are principles which most would argue as sensible - avoiding distortions, creating certainty so individuals and business can plan, and maintaining civil liberties - which are entirely absent and would significantly change his policy prescriptions.
Despite the title, the more stimulating parts of the book are about monetary policy, which to be fair Murphy regards, in a country with its own sovereign currency, as inextricably linked with fiscal policy and hence taxation.
As with many similar polemic books, the author has a habit of announcing his "discovery" of things that are hardly a secret, for example, that banks create money by making loans. The Bank of England apparently "had to admit this in 2014" only after reading Murphy's blog - he's so proud of this he repeats it three times. In reality, Charles Goodhart, a founding member of the post-independence Monetary Policy Committee at the Bank was writing about this in 1984 ("Monetary Theory and Practice").
More contentiously he seems to regard Government debt as a free money making machine. "To regard Government debt as some sort of burden on future generations is absurd" we are told - and justifies this by pointing out that much Government debt is held by pension funds. Those would, of course, be the same pension funds whose main purpose is to transfer wealth from future generations to pensioners by owning claims on assets.
Instead he argues strongly that governments could, in theory, not tax at all and simply print money. But then oddly - and this is where despite claiming to be broadly neutral on a left-right spectrum - he then takes an odd lurch. Far from eliminating distortions "the tax system is designed to have an economic impact and so must be big enough to deliver it." - the joy of tax indeed.
He quite rightly argues for the need for fiscal stimulus in a balance sheet recession (see Richard Koo and his argument that the "government as borrower of last resort") and I have sympathy with his view that using QE to fund infrastructure spending and targeted fiscal boosts (tax cuts for those most likely to spend it) would be a sensible policy to boost demand, if conventional and unconventional monetary tools fail. But crucially this needs to be a temporary not a permanent feature
One of his key arguments is that "all the money we ever need to make things happen can be created out of thin air". The threat of thereby debasing currency - either by domestic inflation or by depreciation - seems not to concern him. Inflation is dismissed as a relic of the past which "isn't prevalent in modern economies" - but of course that is in part because modern economies are run with independent central banks specifically tasked with keeping inflation under control, whereas past inflation was in the era where Governments printed money to fund deficits. And devaluation - a loss of worldwide purchasing power - merits nary a mention.
Murphy would counter that QE hasn't had the same effect but this was a temporary policy, introduced at the height of a global financial crisis, and implemented by an independent central Bank whose very mandate gives them a low - but non-zero - inflation target. A permanent tool in the hands of politicians is likely to have a rather different impact.
He does effectively dismiss the libertarian view of tax stating correctly that tax revenue "does not become the property of some alien body. It is the property of a government in which we have a stake, and in which we participate." However this libertarian view is much more prevalent in the US than UK. More pertinently for the domestic situation, Murphy goes on to argue that "every time a politician says they are spending taxpayers' money they are making another statement that is simply untrue. Tax is not taxpayers' money. It is the government's money" - technically true but his own grammar defeats his logic. Tax revenue is, he is right, the money of taxpayers plural (not the money of the individual taxpayers) given his own logic that taxation is linked with representation, and the "spending taxpayers' money" mantra is quite right to suggest that those entrusted with the funds should spend them prudently and efficiently. There is no joy in tax for taxes sake for most people, other than Mr Murphy it seems.
The distorting effect of taxes are actually in his view a good thing, as stated above, as is constant tinkering with the system "having levers to pull is vital." rather than the certainty and stability which most would regard as sensible features of a well designed system.
Indeed tax should in his world view be used it seems mainly to tax "harmful" things out of existence - to the author these include landlords (not needed - state can print fee money to build as many houses as needed), banks and the financial sector generally, large private limited companies as well as the necessity for anyone to actually work (no need given the Government can hand out free money).
Practicality - in particular the "I wouldn't start from here" point - seems to also pass him by in his overly simplistic approach. Advocating abolish national insurance is hardly news: successive Treasury teams in the last 30 years have tried but failed to find a way of doing it without creating new distortions, a backlash from the losers (which can't always be the "rich" / "bankers", and "landlords") who end up needing to be compensated, and a hole in the Government finances (albeit Murphy doesn't seem concerned re the latter point). The last great theoretical attempt for a clean-sheet approach to changing UK tax was the Community Charge (aka poll tax), and we all know where that ended.
Similarly civil liberties are for the birds - in his world we would have armies of tax inspectors in every town with full access to everyone's private bank accounts - rather vital since his big idea is a transaction tax any time money moves in or out of anyone's account.
Wealth taxes and income taxes are the same thing he says - "the reality is that as far as anyone is concerned (and I stress anyone) £1 of accumulated wealth is identical in economic value to £1 from any other source." But then he explains this using realised capital gains (my emphasis) versus inccome. Fair enough. but there is a massive difference to anyone (and now I stress anyone) in £1 of cash income, and £1 of extra paper wealth apparently accumulated by Zoopla revaluing your property. And yet he uses his argument to support wealth taxes based on Zoopla like data.
He is on stronger grounds in arguing for realised capital gains, even on residences, to be taxed as income. But he discusses inflation indexation of capital gains and admits there were reasons for having it, otherwise "people would be taxed not on their wealth but on the falling value of their money" but as apparently inflation has been abolished he argues this is no longer needed.
Overall Murphy concludes correctly that tax is integral to the contract between a government and the people "that tax must reflect the values and priorities of the people. If it does people will willingly pay it and return the government that charges it to power.". The results of the 2015 General Election and the current polls (November 2015) are rather inconvenient then for his own policy prescriptions.