In each tax household, the number of equivalent adults composing it is counted :
- the first adult counts for 1 ;
- the other persons aged 14 and over for 0.5 ;
- children under 14 for 0.3.
When studying taxable income, this measurement unit is used to calculate household income in relation to the size and age structure of the household. It is recommended for comparing income levels between geographical zones and for analysing income inequalities within a given geographical zone. This equivalence scale is widely used by Insee and Eurostat.