- Methods and Projects
- Standards and Classifications
Standardised Methodological Report
Annual Wage Structure Survey
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1Contact
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1.1Contact organisation
National Statistics Institute of Spain
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1.5Contact mail address
Avenida de Manoteras 50-52 - 28050 Madrid
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1.1Contact organisation
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2Metadata update
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2.1Metadata last certified
09/05/2025
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2.2Metadata last posted
20/06/2023
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2.3Metadata last update
09/05/2025
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2.1Metadata last certified
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3Statistical presentation
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3.1Data description
The Annual Wage Structure Survey (AWSS) is an annual statistical operation that has arisen out of the need for annual wage information classified by sex. It is the source of information for the compilation of the "Gender Pay Gap" Structural Indicator requested each year by Eurostat.
The legal basis for the preparation of this statistical operation is the same basis regulating the Wage Structure Survey that is conducted every four years, allowing the integration of the results for both statistics, though the number of variables studied in the annual operation is smaller.
The objective of the Annual Wage Structure Survey is to ascertain the wage distribution, based on individual and collective characteristics.
It provides estimates of the gross annual earnings per worker, classified by different characteristics, such as sex, occupation, economic activity, age, etc.
The survey enables offering results, both on a national level and by Autonomous Community.
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3.2Classification system
- Clasificaciones utilizadas
The survey uses the National Classification of Economic Activities, CNAE-2009, and the National Classification of Occupations NCO-11.
- Clasificaciones utilizadas
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3.3Sector coverage
The sectoral coverage encompasses from Section B to Section S of CNAE-2009.
The occupation coverage includes those occupations included in Large Groups 1 to 0 from NCO-11.
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3.4Statistical concepts and definitions
- Age
Age in years refers to the number of birthdays reached by the reference date, in other words, the age last birthday.
- Citizenship
Citizenship is defined as the particular legal bond between an individual and his/her State,, acquired by birth or naturalisation, whether by declaration, option, marriage or other means according to the national legislation.
- Earnings per normal working hour
This is obtained from annual gross earnings divided by the the number of hours paid during the same period. This is necessary for studying, under equal conditions, workers with different working days, especially part-time workers.
- Gross annual earnings in the reference year
Gross annual earnings cover remuneration in cash and in kind paid during the reference year before any tax deductions and social-security contributions payable by wage earners and retained by the employer.
The main difference between annual and monthly earnings is that annual earnings are not only the sum of the direct remuneration, bonuses and allowances paid to an employee in each pay period. Annual earnings hence usually exceed the figure produced by multiplying the "standard monthly package" by 12.
The "standard monthly package" includes those bonuses and allowances which occur in every pay period, even if the amount for these "regular" bonuses and allowances varies, but excludes bonuses and allowances not occurring in every pay period. Furthermore, monthly earnings leave payments in kind out of consideration. However, annual earnings also cover all "non-standard payments", i.e. payments not occurring in each pay period (variable 4.1.1), and payments in kind (variable 4.1.2).
Data for variable 4.1 should be provided for all employees for whom gross monthly earnings (variable 4.2) can be supplied, i.e. variable 4.1 should not be provided for employees for whom an estimate of an employee¿s gross monthly earnings is not feasible. These employees will be excluded from the sample.
It does not matter if the employee¿s earnings do not always relate to a full year. Some employees will have periods of unpaid absence, or will have joined or left the enterprise during the year. The actual gross earnings in the reference year are required. When variable 3.1 (number of weeks to which the annual earnings relate) is less than 52 weeks, variable 3.1 will be used to gross up variable 4.1 and its components. - Interprofessional Minimum Wage (IMW)
The Interprofessional Minimum Wage (IMW) establishes the minimum amount of remuneration that a worker will receive, in reference to the legal working day. Each year, following consultation with the most representative Trade Unions and business associations, the Government regulates the "Interprofessional Minimum Wage", for both permanent workers and temporary workers, as well as for the personnel serving family households, bearing in mind the Consumer Price Index, the average national productivity achieved, the increase in job participation in national income, and the general current economic status.
- Sex
Sex refers to the biological sex of the person. According to the WHO, "sex" refers to biological and physiological features defining to men and women, whereas "gender" refers to the roles, behaviour, activities and attributes constructed socially that a specific culture regards as appropriate for men and women. In accordance with this description, the WHO regards "man" and "woman" as sex categories, whereas "male" and "female" are gender categories.
- Social Security contribution account
This is composed of a group of workers employed by others, who carry out their employment activity in one or more workplaces at a single company, within a single province and generally under a single main activity, although not necessarily so, and with standard features as regards Social Security contribution.
- Age
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3.5Statistical unit
The survey uses two types of statistical unit:
1. The Contribution Accounts included in the General Register of Social Security Contribution Accounts.
The Social Security Contribution Account is a concept traditionally used in wage and labour cost surveys, both by the INE and by other bodies with jurisdiction in this area.
2. The workers employed by others associated with the Contribution Accounts.
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3.6Statistical population
The target contribution accounts of study are those whose economic activity belongs to Sections B to S of CNAE-2009, and which are in the General Register of Social Security Contribution Accounts at 30 September of the reference year.
The workers included in the survey are those who work for others in target contribution accounts of study of the survey, and who have been registered in Social Social at least two months of the year, with one of those months being October. The inclusion of this month is due to the advantage of being considered "normal" in all EU countries, in the sense that it is scarcely affected by seasonal variations or by payments with a due date longer than a month, such as the Christmas payments.
It excludes all chairpersons, members of administrative boards, and in general, all personnel whose remuneration is not mainly in the form of wages, but rather commissions or benefits.
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3.7Reference area
The geographical scope encompasses the entire national territory, with results broken down by Autonomous Community.
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3.8Time coverage
The survey is carried out annually. Results thereof are available as of the year 2004. The data referring to years 2006, 2010, 2014, 2018 and 2022 has been obtained from the Wage Structure Survey, which is conducted every four years, rather than the Annual Wage Structure Survey.
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3.9Base period
The Annual Wage Structure Survey has been affected by numerous methodological changes, due to the implementation of new classifications in both economic activity and occupation. As a result, the last homogeneous series began in 2008, using the National Classification of Economic Activities, CNAE-2009, and the National Classification of Occupations, NCO-11.
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3.1Data description
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4Unit of measure
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4.1Unit of measure
Euros
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4.1Unit of measure
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5Reference period
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5.1Reference period
The data refers to the target calendar year of the survey.
Data referred to the period: Anual A: 2023
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5.1Reference period
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6Institutional mandate
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6.1Legal acts and other agreements
The compilation and dissemination of the data are governed by the Statistical Law No. 12/1989 "Public Statistical Function" of May 9, 1989, and Law No. 4/1990 of June 29 on “National Budget of State for the year 1990" amended by Law No. 13/1996 "Fiscal, administrative and social measures" of December 30, 1996, makes compulsory all statistics included in the National Statistics Plan. The National Statistical Plan 2009-2012 was approved by the Royal Decree 1663/2008. It contains the statistics that must be developed in the four year period by the State General Administration's services or any other entity dependent on it. All statistics included in the National Statistics Plan are statistics for state purposes and are obligatory. The National Statistics Plan 2025-2028, approved by Royal Decree 1225/2024, of 3 December, is the Plan currently implemented. This statistical operation has governmental purposes, and it is included in the National Statistics Plan 2025-2028. (Statistics of the State Administration).
Council Regulation no. 530/1999, of 9 March 1999, relating to structural statistics on wage earnings and wage costs.
Commission Regulation no. 1738/2005, of 21 October 2005, amending Regulation (EC) no. 1916/2000, referring to the definition and transfer of information regarding the structure of wage earnings.
The Spanish version of the European Union regulations affecting this statistical operation is available at:
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6.2Data sharing
The exchanges of information needed to elaborate statistics between the INE and the rest of the State statistical offices (Ministerial Departments, independent bodies and administrative bodies depending on the State General Administration), or between these offices and the Autonomic statistical offices, are regulated in the LFEP (Law of the Public Statistic Function). This law also regulates the mechanisms of statistical coordination, and concludes cooperation agreements between the different offices when necessary.
In order to conduct this survey, administrative register data from the General Social Security Treasury, the State Tax Administration Agency and the Tax Agencies of Navarra, Bizkaia, Gipuzkoa and Araba is used.
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6.1Legal acts and other agreements
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7Confidentiality
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7.1Confidentiality - policy
The Statistical Law No. 12/1989 specifies that the INE cannot publish, or make otherwise available, individual data or statistics that would enable the identification of data for any individual person or entity. Regulation (EC) No 223/2009 on European statistics stipulates the need to establish common principles and guidelines ensuring the confidentiality of data used for the production of European statistics and the access to those confidential data with due account for technical developments and the requirements of users in a democratic society
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7.2Confidentiality - data treatment
INE provides information on the protection of confidentiality at all stages of the statistical process: INE questionnaires for the operations in the national statistical plan include a legal clause protecting data under statistical confidentiality. Notices prior to data collection announcing a statistical operation notify respondents that data are subject to statistical confidentiality at all stages. For data processing, INE employees have available the INE data protection handbook, which specifies the steps that should be taken at each stage of processing to ensure reporting units' individual data are protected. The microdata files provided to users are anonymised.
The tables published do not show data in those cells whose estimation is supported by fewer than 100 sample observations.
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7.1Confidentiality - policy
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8Release policy
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8.1Release calendar
The advance release calendar that shows the precise release dates for the coming year is disseminated in the last quarter of each year.
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8.2Release calendar access
The calendar is disseminated on the INEs Internet website (Publications Calendar)
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8.3User access
The data are released simultaneously according to the advance release calendar to all interested parties by issuing the press release. At the same time, the data are posted on the INE's Internet website (www.ine.es/en) almost immediately after the press release is issued. Also some predefined tailor-made requests are sent to registered users. Some users could receive partial information under embargo as it is publicly described in the European Statistics Code of Practice
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8.1Release calendar
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9Frequency of dissemination
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9.1Frequency of dissemination
The survey is disseminated annually.
It must be noted that the data referring to the years 2006, 2010, 2014, 2018 and 2022 is from the Wage Structure Survey, and it is totally comparable with that obtained in the remaining years.
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9.1Frequency of dissemination
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10Accessibility and clarity
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10.1News release
The results of the statistical operations are normally disseminated by using press releases that can be accessed via both the corresponding menu and the Press Releases Section in the web
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10.2Publications
Users may access the data via the INE website. Specifically, the data appears in the following links:
- Press release: this contains a summary of the results obtained in the reference year.
- Results of detailed: this contains the series compiled in CNAE-2009 and NCO-11.
- Related links in INEbase: this is where the series compiled in classifications used in previous years are presented. There are two sections:
1. Detailed CNAE-2009/NCO-94 results: 2008-2009 Series.
2. Detailed CNAE-93/NCO-94 results: 2004-2007 Series.They include information from free online publications of the AWSS, such as: "Spain in Figures," "Statistical Yearbook of Spain," etc.
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10.3On-line database
INEbase is the system the INE uses to store statistical information on the Internet. It contains all the information the INE produces in electronic formats. The primary organisation of the information follows the theme-based classification of the Inventory of Statistical Operations of the State General Administration . The basic unit of INEbase is the statistical operation, defined as the set of activities that lead to obtaining statistical results on a determined sector or subject based on the individually collected data. Also included in the scope of this definition are synthesis preparation.
The tables and time series may be accessed in INEbase, within the Society/Labour market section, and through the following link:
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10.4Micro-data access
A lot of statistical operations disseminate public domain anonymized files, available free of charge for downloading in the INE website Microdata Section
No anonymised microdata file is provided for this statistical operation.
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10.5Other
There is the option of requesting tailor-made information from the INE Customer Service Area. Limitations to confidentiality or precision are borne in mind at the time of processing said requests.
The link to the INE Customer Service Area is as follows:
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10.6Documentation on methodology
For a detailed description of the methods and concepts used, as well as of other documents related to the Annual Wage Structure Survey, please see the following webpage:
AC3=100%.
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10.7Quality documentation
Fields 10.6 to 17 of this document may be considered the quality report intended for users for this operation.
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10.1News release
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11Quality management
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11.1Quality assurance
Quality assurance framework for the INE statistics is based on the ESSCoP, the European Statistics Code of Practice made by EUROSTAT. The ESSCoP is made up of 16 principles, gathered in three areas: Institutional Environment, Processes and Products. Each principle is associated with some indicators which make possible to measure it. In order to evaluate quality, EUROSTAT provides different tools: the indicators mentioned above, Self-assessment based on the DESAP model, peer review, user satisfaction surveys and other proceedings for evaluation.
The compilation process of the statistics has established controls for detecting and correcting errors, for the purpose of guaranteeing the quality thereof from the beginning of the process onward. The collection, recording and filtering processes of the information are fundamental stages in the development of any statistical research.
Prior to processing the information, a comprehensive control of the data provided by the respondent units is performed, in order to ensure the validity thereof.
The data received passes through a dual control:
- A first filtering, simultaneous to the recording, which has the objective of detecting incomplete and erroneous questionnaires, as well as guaranteeing the coherence of the data recorded.
- A second control, in order to avoid inconsistency between related variables obtained from the surveys and from the administrative registers, which is combined with a macrofiltering based on the elevated data obtained.Once all of the information is validated, macrofiltering analyses are performed, using the results obtained and their comparison with previous periods.
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11.2Quality assessment
The Annual Wage Structure Survey is a high-quality product. Its sample size allows for offering indicators up to a regional level, within reasonable sampling errors, and provides a particularly valuable measurement of wage evolution.
Regarding the limitations of the survey, it is important to point out those that are inherent to statistical operations by sampling, such as non-response and the aforementioned sampling errors or variation coefficients of the estimates. In both cases, they remain within reasonable limits.
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11.1Quality assurance
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12Relevance
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12.1User needs
Survey users include:
- Eurostat.
- Ministries and other public bodies.
- Territorial administrations (Autonomous Communities, municipal councils, etc.).
- Businesses and non-profit institutions, trade unions and employers' organisations.
- Researchers and universities.
- Individuals.
Each one of these users has different needs, according to the purpose and use they will make of the information they require.
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12.2User satisfaction
The INE has carried out general user satisfaction surveys in 2007, 2010, 2013, 2016 and 2019 and it plans to continue doing so every three years. The purpose of these surveys is to find out what users think about the quality of the information of the INE statistics and the extent to which their needs of information are covered. In addition, additional surveys are carried out in order to acknowledge better other fields such as dissemination of the information, quality of some publications...
On the INE website, in its section Methods and Projects / Quality and Code of Practice / INE quality management / User surveys are available surveys conducted to date.(Click next link)
The INE has carried out general user satisfaction surveys in 2007, 2010, 2013, 2016 and 2019 and it plans to continue doing so every three years. The purpose of these surveys is to find out what users think about the quality of the information of the INE statistics and the extent to which their needs of information are covered. In addition, additional surveys are carried out in order to acknowledge better other fields such as dissemination of the information, quality of some publications...
On the INE website, in its section Methods and Projects / Quality and Code of Practice / INE quality management / User surveys are available surveys conducted to date.(Click next link)
In the Satisfaction surveys carried out on users, the "Labour Market" group can provide us with indications on the opinion of the users of this statistical operation. The most important users, the Commission and the European Central Bank, generally indicate satisfaction, but they want shorter timeframes in the publication of information.
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12.3Completeness
The Annual Wage Structure Survey is a fundamental source of information for the preparation of the "Gender Pay Gap" Structural indicator, and therefore, it is subject to regulation by said indicator. Therefore, the rate of compulsory information provided is R1=100%.
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12.1User needs
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13Accuracy and reliability
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13.1Overall accuracy
The sample design tries to minimise the sampling errors, and the different survey processes are aimed at eliminating, or reducing as much as possible, the errors thereof, both in the collection phase (response rate and filtering control) and in the subsequent editing and imputation phases.
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13.2Sampling error
The calculation of variation coefficients of the main variables is carried out each time the survey is compiled, and they are disseminated in its publication and in subsequent quality reports.The variation coefficients of the annual earnings by gender are: "Annual earnings" A1=0.36%; "Annual earnings, male" A1=0.48%;"Annual earnings, female" A1=0.53%.
For greater detail, please see section 5 of the survey publication:
https://www.ine.es/dynt3/inebase/es/index.htm?padre=4563&capsel=4566
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13.3Non-sampling error
Non-sampling errors are controlled throughout the entire statistical process.
The Annual Wage Structure Survey is collected in parallel with the Quarterly Labour Cost Survey, as the former is a subsample of the latter. Therefore, for further information regarding non-sampling errors, it suffices to see this section in the QLCS metadata: https://www.ine.es/dynt3/metadatos/en/RespuestaDatos.htm?oe=30187
Item non respose is not allowed. The average non-response rate for the reference period data has been A4=8.0% of the units representing 3% of the employees.
In cases of non-response, the imputation of the occupation is performed, using other available variables on the employees. A7=2.9%
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13.1Overall accuracy
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14Timeliness and punctuality
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14.1Timeliness
The data for the statistics is published 17 months following the end of the information reference period. Commission Regulation (EC) No 1916/2000 of 8 September 2000 on implementing Council Regulation (EC) No 530/1999 concerning structural statistics on earnings and on labour costs as regards the definition and transmission of information on structure of earnings requires the availability of results within 18 months of the end of the reference period. This objective is met.
TP2=17 months
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14.2Punctuality
The dissemination of the data is carried out in accordance with the structural statistics availability calendar that the INE compiles and publishes for each year.
TP3= 100%.
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14.1Timeliness
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15Coherence and Comparability
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15.1Comparability - geographical
The availability of a methodology, a design and a common process for the collection, filtering, editing and elevation for the entire geographical scope, guarantees the comparability of the results among the different Autonomous Communities.
The international comparability of the data provided by this statistical operation is guaranteed, as it is carried out following the existing community regulations.
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15.2Comparability - over time
The results, broken down by CNAE-2009 section and sector, are comparable over time as of the year 2008, and therefore, there are CC2=16 comparable elements.
The results, broken down by CNO-2011 main occupation group, are comparable over time as of the year 2008, and therefore, there are CC2=16 comparable elements.
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15.3Coherence - cross domain
The use of the same national classification of economic activities allows for the possibility of contrasting the information with other statistics on common variables, such as the Living Conditions Survey.
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15.4Coherence - internal
The estimates of the Annual Wage Structure Survey have complete internal coherence, since they are based on the same microdata set and are calculated using the same estimation methods. The arithmetic and accounting identities in the production of data sets are observed.
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15.1Comparability - geographical
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16Cost and burden
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16.1Cost and burden
The use of administrative registers in this statistical operation leads to a considerable reduction in the response burden.
The fact that the Annual Wage Structure Survey is collected together with the Quarterly Labour Cost Survey leads to the fact that all of the actions performed in order to avoid an excessive response burden in this survey affect the Annual Wage Structure Survey.
The estimation of the budgetary credit necessary to finance these statistics, as foreseen in the 2025 Annual Programme, comes to a total of 544.4 thousand euros.
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16.1Cost and burden
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17Data revision
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17.1Data revision - policy
The INE of Spain has a policy which regulates the basic aspects of statistical data revision, seeking to ensure process transparency and product quality. This policy is laid out in the document approved by the INE board of directors on 13 March of 2015, which is available on the INE website, in the section "Methods and projects/Quality and Code of Practice/INE’s Quality management/INE’s Revision policy" (link).
This general policy sets the criteria that the different type of revisions should follow: routine revision- it is the case of statistics whose production process includes regular revisions-; more extensive revision- when methodological or basic reference source changes take place-; and exceptional revision- for instance, when an error appears in a published statistic-.
There is no data revision.
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17.2Data revision - practice
The data is published when it is final. It is not subject to revision.
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17.1Data revision - policy
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18Statistical processing
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18.1Source data
The Annual Wage Structure is a combination of the use of administrative registers and the conduction of a direct survey.
The random sampling process of units corresponds to a stratified two-stage sampling, where the first-stage units are the Social Security contribution accounts, while the second-stage units are the workers.
The sample selected in the first stage is the same as that selected in the Quarterly Labour Cost Survey. A stratified random sampling with optimal allocation is used, in which the sample units are the contribution accounts. The stratification criterion is performed, based on three variables: the Autonomous Community (17 in total, considering Ceuta and Melilla together with Andalucía), the economic activity (CNAE-2009 division, 82 divisions in total) and the size of the units (8 strata or size groups).
The size of the units is defined by the number of workers grouped therein. The following groups are considered for the stratification: 1-4 workers; 5-9 workers; 10-19 workers; 20-49 workers; 50-99 workers; 100-199 workers; 200-499 workers; 500 workers or more.
The strata with 500 workers or more are studied comprehensively. Within each stratum, the units are selected via systematic random-start sampling.The list of units selected in the first stage is submitted again to the General Social Security Treasury, and the list of workers who were registered during the reference year is obtained.
This list is used to select the workers, where the number of workers to be selected in each centre depends on the total wage earners in said centre who have been registered in Social Security for at least two months, one of them being October. The selection is performed via systematic sampling, within each contribution account, with the lists of workers being previously ordered, first by Social Security contribution account, and with each contribution group, by sex, in such a way that the representativeness of the sample is ensured.The information relating to the occupation of the workers is obtained from the questionnaires, and in the case of workers from País Vasco, the information relating to the annual earnings of said workers is also obtained. The rest of the information on earnings is obtained through requests made of the State Tax Administration Agency and the Tax Agency of Navarra.
The sample comprises some 28,000 contribution accounts, and approximately 250,000 workers.
For further information, please see the website:
https://www.ine.es/en/metodologia/t22/t223013310a_en.pdf
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18.2Frequency of data collection
The data collection is annual, regardless of whether it is that carried out by direct survey or that which comes from the administrative registers.
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18.3Data collection
The respondent contribution accounts answer the survey questionnaire either online, by ordinary post (questionnaires filled out on paper); or by e-mail.
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18.4Data validation
The first stage of data validation is carried out in the data collection centres, in which errors and inconsistencies in the information received from the respondent units is detected.
Subsequently, a second validation stage is performed by adding the data obtained from the respondents to that obtained from administrative registers.
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18.5Data compilation
In cases of non-response, the imputation of the occupation is performed, using other available variables on the workers.
In order to obtain the elevated results, it uses separated ratio estimators, using the number of workers in the Social Security Contribution Account Directory as an auxiliary variable.
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18.6Adjustment
No seasonal adjustments are carried out.
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18.1Source data
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19Comment
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19.1Comment
(.)
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19.1Comment