The income groups are based on standardised disposable income. This is the gross income of all members of a household, minus income transfers, premiums and taxes. The resulting amount is then corrected for the size and the composition of the household. This standardised disposable income, or purchasing power, is then assigned to every member of the household.. On the basis of standardised income, people can be divided into five income groups. The lowest income group comprises the 20 percent of people with the lowest income (1st quintile) and the highest income group comprises the 20 percent of people with the highest income (5th quintile). Back to article