The survey sample is made up of respondents to the Labour Force Survey (EEC) of the 4th quarter of the year N. A statistical match is made with the tax sources for the year N, i.e. the tax returns for year N (completed in March N+1) and the local residence tax (on 1st January N+1) provided to the INSEE by the fiscal administration.

Some further improvements have been applied to the former Tax Income Survey (ERF) in line with the recommendations of the 2007 report on standards of living and inequalities by the French National Statistical Information Council (CNIS) - which is the body that prepares the annual agenda for the INSEE.

In the Tax Income Survey (ERF), non-taxable social incomes (family-related allowances, housing allowances and minimum social benefits) were deemed to be estimated according to a computation schedule taking into account the type of household or by econometric simulation.

In the new series, called the Tax and Social Incomes Survey (ERFS), the amounts actually received by the households over the reference year N are collected directly from the three main Benefit funds in France : the national family allowances fund (CNAF), the national old-age insurance fund (CNAV) and the central agricultural social insurance fund (CCMSA). These data are matched with the survey - household by household - thanks to a statistical operation of merging.

Moreover, the old series of Tax Income Surveys which relied exclusively on fiscal sources did not properly assess investment incomes, mainly because these incomes are not to be recorded on tax returns, and therefore minimised the income inequalities that could be measured.

In addition to the first improvement, the incomes that are generated by several financial products and are not to be recorded on the tax returns are now imputed using stochastic imputation models.

Imputation models rely on models of financial asset holdings patterns that are first estimated on microdata from the Household Wealth Survey. Incomes from such assets are then computed based on average return rates that are applied to these assets amounts.