The Economist had a very informative graphic which looked at the change in the Gini coefficient after taxes and transfers. The Gini Coefficient is derived from the same information used to create a Lorenz Curve. The co-efficient indicates the gap between two percentages: the percentage of population, and the percentage of income received by each percentage of the population. In order to calculate this you divide the area between the Lorenz Curve and the 45° line by the total area below the 45° line eg.
Area between the Lorenz Curve and the 45° line
Total area below the 45° line
The resulting number ranges between:
0 = perfect equality where say, 1% of the population = 1% of income, and
1 = maximum inequality where all the income of the economy is acquired by a single recipient.
* The straight line (45° line) shows absolute equality of income. That is, 10% of the households earn 10% of income, 50% of households earn 50% of income.
The comparison before and after taxes and transfer gives an indication of how they benefit the levels of inequality in an economy.
America’s tax system is progressive and as the its pre-tax Gini coefficient is high the government has to spend more on transfer payments to reduce inequality. In contrast, countries with low pre-tax inequality, such as South Korea, manage to achieve low post-tax inequality without doing much by way of redistribution. Note that the graph from The Economist is on a scale of 0 – 100. 100 being maximum inequality.
The significance of government spending has a big impact on a country’s Gini coefficient. The Economist note that both France and the US have similar levels of inequality before tax but after taxes France reduces inequality from 45 to 28 whilst the US reduces it from 47 to 38 approximately. In France government spending accounts for 57% of GDP. America’s federal, state and local authorities spend just 35%.
New Zealand has a Gini coefficient of 42 whilst after taxes and transfers goes down to 34.
Ireland does most to slash inequality. After taxes and transfers, Ireland’s income distribution goes from 50 to 30 – the higher income groups pay more in tax than in most other countries, while low-earning households receive generous tax credits and transfer payments. Part of the reason Ireland is able to do so much redistribution is that it relies more than most on taxes paid by multinational companies. Foreign-owned firms accounted for 80% of corporate tax in 2017. Cross-country data suggest that if America wanted to bring its level of inequality down to the OECD average, it would have to boost government spending to 50% of GDP.
Source: The Economist – April 13th 2019.