Irish tax policy still on a learning curve
Recently the US economist Arthur Laffer was awarded the US Presidential Medal of Freedom by President Trump.
Mr Laffer had a distinguished academic career, but he also enjoyed a position which is far more useful for anyone who wishes to have their ideas catch on.
That is, for several years, he served as a special adviser to various Republican administrations.
When it comes to tax policy, Mr Laffer is best known for his eponymous "curve".
He presented a clever illustration of a relatively simple idea. If the tax rate is zero, no tax is collected.
On the other hand, if the tax rate is 100%, no tax will be collected either.
This is because no one will have any incentive to work and earn, or those that do will be doing their utmost to evade the tax which is charged at 100%.
Between these two extremes there is a point somewhere along the curve which is a sweet spot.
Mr Laffer maintained that there must be a point where the tax rate is not so high as to remove the incentive to work or create a temptation to avoid or evade tax, and not so low that cannot bring in sufficient money to the Exchequer to fund government activities and social programmes.
But, can any 'one size fits all' theory like the Laffer curve apply across the board to all taxpayers, no matter what?
Mr Lafferâs ideas first came to the fore in the 1970s but since then the Laffer curve has had a mixed reception.
Right wing policymakers cite the Laffer curve as justification of low tax rate regimes and as evidence that low tax rates result in greater economic activity and participation in the market by workers and industry alike.
Left-wing critics argue that the theory justifies low tax and spend policies and is, in effect, a taxpayer's charter for the better off.
An immediate problem with the theory is that, given it has existed for some 40 years or so, you might expect that someone would have worked out by now exactly where that tax rate sweet spot is located.
One obvious candidate would be at the 50% point, because when the rate is higher than that, a worker would lose more in tax than they can take home.
Yet, the marginal tax rate in this country - and you have to add in PRSI and the Universal Social Charge in the calculation - was more than 50% for several years after the financial crisis, but still the tax receipts held up.
That may be because most tax in this country is withheld at source; that is, tax is collected as soon as money changes hands.
PAYE workers have no say, whatsoever, over the tax withheld from their wages.
Similarly, the current standard rate of Vat is 23% but no consumer can take a decision to pay Vat at a lower rate than that.
The tax is built into the price of the goods or services being purchased.
Given this type of built-in tax regime, itâs hard to see how the Laffer curve theory - on its own - can predict what the most efficient tax rates should be in a country like Ireland.
Our tax policymakers will have to look a bit further for a magic formula to keep most people paying the most tax for most of the time.
In practice, we just have to get on with whatever rates are determined on Budget Day and reserve our revenge for the next election.
Dr Brian Keegan is director of public affairs at Chartered Accountants Ireland