Undercover Economist

Why tax systems are trickier than Martian algebra

Only radical restructuring has a chance of creating fair taxation, writes Tim Harford

Tax is a divisive subject but everyone seems to agree on one point: taxes are too complicated and should be simpler. Unfortunately, tax systems did not receive the memo.

In the UK only a few years ago, almost everyone in work used to be taxed at a marginal rate of either 31 per cent or 41 per cent, depending on how much they earned. (If Brits do not recognise those numbers, it is because the UK has two cumulative systems of income tax, one of which goes by the code name of “national insurance”.)

The system is trickier today than Martian algebra. Paul Johnson of the Institute for Fiscal studies points out that, over different levels of income, a non-working spouse with two children will be taxed at marginal rates of 12 per cent, 32 per cent, infinity, 42 per cent, 60 per cent, 42 per cent, 60 per cent, 42 per cent and 47 per cent. You might ask what kind of muppet designed a tax schedule like that, and one answer would be George Osborne, chancellor of the exchequer, and Alistair Darling, his predecessor – the last two men to be in charge of the UK tax system.

Another answer would be that this is just the sort of thing that happens without diligent maintenance. Window frames rot. Iron structures rust. Tax systems become complex.

Having nine different marginal tax rates is an ugly sign that things are not well. There are others. Cereal bars attract value added tax at 20 per cent but flapjacks enjoy a zero rate; vegetable chips are tax-free if the vegetable in question is not a potato; dried fruit is subject to VAT unless destined for a cake. On a gingerbread man, chocolate icing attracts a substantial VAT liability unless the icing constitutes the eyes. There are more things in tax accounting, Horatio, than are dreamt of in your philosophy.

If a tax break for unfrosted gingerbread seems uniquely British in its eccentricity, it is not. Officials in New York state have been obliged to rule on the tax status of burritos. (Legally they are sandwiches and attract sales tax of 8 per cent.) Or consider Pillow Pets, a stuffed toy/ pillow whose slogan – “It’s a pillow, it’s a pet, it’s a Pillow Pet” – poses a dilemma for US Customs. For the purposes of levying a tariff, is it a pillow? Or is it a tariff-free toy pet?

Then there are tax subsidies for agricultural land in places such as Florida. Agricultural land is no easier to define than a flapjack or a sandwich. Rent a cow, let it graze on your garden or vacant lot; if that is not agriculture, what is?

All this matters not just because the rules are hard to understand and expensive to obey but also because taxes shape our behaviour. The “camelback” houses of late 19th century New Orleans, with a hump of two storeys at the rear and a long single-storey snout stretching to the street, were tax-efficient because property taxes were levied based on the number of storeys at the front of the house. Abba’s outlandish outfits are reported to have been inspired by tax rules: they were tax-deductible only if they were too outré to be worn anywhere other than on stage.

These are trivial examples of tax-efficient charm but the same principle can be harnessed for a far greater good: a carbon tax to shift our energy system towards low-carbon fuels. Well-designed taxes can raise revenue while rewarding green behaviour.

Meanwhile complex, illogical taxes raise less revenue while rewarding clever accountants. There has been outrage over celebrity tax-dodging in the UK but the tax avoidance schemes usually involve a government attempt to provide a tax incentive for the British film industry or some other hobbyhorse.

What is behind such insanities? Partly, absurd loopholes exist because special interest groups demand them; hence the subsidies for land with cows on it. Partly, voters are given the tax systems they deserve because we sympathise with highly vocal losers whenever a loophole is closed and we fall for simple tricks that hide taxes behind a veil of complication.

The UK’s two-tier income tax system is a good example. Basic income tax rates have tended to fall over time, while national insurance rates have tended to rise. True income tax rates for the typical worker are similar to those of 35 years ago but they seem much lower. The sleight of hand is politically convenient but increases complexity, creates unfairness and opens opportunities for tax avoidance.

It is tempting, then, to call for a radical simplification, for taxes simple enough to write on the back of a postcard. But this ignores the third reason that taxes are complex, which is that fair taxation is a genuinely complex business. This year’s piecemeal reform efforts become next year’s loopholes.

Only radical, systemic reform has much chance of success – and it may be less elegant than some reformers hope. A per-person “poll tax” was introduced in the UK 25 years ago, and promptly ended the premiership of Margaret Thatcher. It was undoubtedly simple – but in taxation, as in life, simplicity is not the only virtue.

Also published at ft.com.