Basic information on the methodology of the survey of employment-related population movements in 2006
1. The survey, in accordance with the provisions of the Programme of statistical surveys for official statistics 2008, was prepared on the basis of data made available by the Ministry of Finance.
2. The provided set included data from tax forms prepared by employers concerning the year 2006:
2.1 PIT-11/8B – Information concerning income and advance income payments,
2.2 PIT-40 – Annual calculation of tax on income obtained by the taxpayer in the given tax year.
3. The methodology of the survey provides for several levels of work:
3.1 The set was subject to formal and logical control, i.e. the completeness of entries in points referring to the withholding agent and the taxpayer were checked (including the NIP number of the withholding agent and the taxpayer), and the accuracy and completeness of points defining the period to which the document refers, as well as the logical connotations between the entry in the section “Information on costs of obtaining revenues” and the actual (expressed in amounts) costs of obtaining revenues provided in the section “the income of the taxpayer and the advance income payment by the withholding agent”.
3.2 On the assumption that the so-called critical point of the survey will be 31 XII 2006, the set was limited to records which included this date as the point closing the settlement period.
3.3 Work involving the checking the conformity of entries concerning the address data of the withholding agent and the taxpayer with the applied territorial symbols from the TERYT register was performed. The basic unit in the survey was gmina (commune).
In the survey of population movements the relationship between urban and rural areas is significant, so in the case of urban-rural gminas, a division was made into the urban and the rural part of the gmina.
3.4 The prepared set of records was the basis for generating a database with the unique NIP (Tax Identification Number) numbers of taxpayers for whom the source of revenue in 2006 was hired work (records which in the section concerning revenue has a completed entry concerning wages and salaries on the basis of employment, service, cooperative and outworking relationships, as well as financial benefits from social insurance paid by the work establishment). At the same time, duplicated NIP numbers of taxpayers with a completed entry on wages and salaries were removed with the use of the amount-of-income criterion.
3.5 In this way the set of taxpayers was created, counting 9.5 million persons in national terms. It constituted a database from which the population of persons commuting to work was separated out.
3.6 According to the accepted definition, persons commuting to work should meet the following conditions: they work in a different gmina from the gmina of their residence and, simultaneously, the costs of obtaining revenues due to commuting to work were increased. The set of persons meeting the above-mentioned criteria numbered 2.3 million persons in national terms.
3.7 In addition, the results of the survey concerning the directions of movements were adjusted on the basis of information included in the Statistical Units Database.