The Wage Structure Survey is a four-yearly statistical operation (based on the 2002 Survey results), carried out within the framework of the European Union with common methodology and content criteria, for the purpose of obtaining comparable results on the structure and distribution of wages between Member States. This survey researches wage distribution, considering a large variety of variables such as sex, occupation, branch of activity, seniority or company size.

This survey has been conducted for reference years 1995 and 2002. The data for the year 2006 are being presented now, with the main innovations being the broadening of the survey to small work centres (with 1 to 9 workers) and the including of information on payments in kind.

Beginning in the year 2004, and in those years when the four-yearly survey is not conducted, the Annual Wage Structure Survey obtains estimates of the gross annual earnings per worker, classified by type of working day, sex, economic activity according to NACE-93 and occupations to one digit of NCO-94.

The information is obtained through the combined processing of the Social Security General Affiliation File (SS) and Model 190 statements: Annual Summary of Withholdings and Advance Payments on Personal Income Taxes by the State Tax Administration Agency (AEAT) and the Treasury of Comunidad Foral de Navarra, along with the occupation and work time variables provided by the survey attached to the INE Quarterly Labour Cost Survey.

In order to facilitate the compilation of time series, in the year 2006, the same tables compiled for the rest of the years were included in this section, but using the information from the four-yearly survey.