B. Current challenges and good practices in the organization of data compilation
10.17. Statistical work programme in preparation of a customs union. The experiences of the European Union, SACU, COMESA and ASEAN indicate that the preparation for a customs union requires at least (a) the adoption of an uniform nomenclature of goods, (b) uniform rules of origin and (c) uniform customs valuation and uniform application of certain custom procedures to allow for the uniform application for external tariffs (which are by many countries applied at a more detailed level than the HS six-digit level). Also, the clarification of the customs territory (and, accordingly, the statistical territory) appears to be an essential requirement as all members need to be aware of what territories are included and not included in the customs union. The harmonization of other elements relevant for data compilation such as coverage, trade system, detailed customs procedures, partner-country attribution, quality assurance, etc., might depend on the requirements and use of the data compiled by countries. The establishment of a central statistical body which is in charge of the above tasks is important and represents good practice in respect of ensuring the provision of high-quality extra- and intra-trade statistics required for the effective functioning of a customs union.
10.18. Loss of customs information on intra-union trade. The abolition of customs controls within a customs union means that no customs records will be available for the compilation of information on trade between members of a customs union. Possible data sources are administrative records which might be available from taxation (value added or sales tax) or from surveys of exporters and importers. In most countries, the overwhelming majority of exports are conducted by medium-sized or large enterprises which might be very limited in number and which may relatively easily be surveyed. The imports of certain goods might be equally concentrated, i.e., conducted by a few national importers, retailer or wholesale. However, an increasing proportion of imports might result from direct transactions between consumers and Internet retailers, which arrange for a direct shipment to the individual consumer. In such situation, the implementation of surveys might be more difficult and costly.
10.19. Challenges for the compilation of extra-union trade. In the European Union, which is the most developed customs union, statistical data collection remains the responsibility of individual member States. Statistics on extra-union trade is therefore a combination of the national statistics of all member countries. In order for statistics of the members to be combined into reliable extra-union statistics, it is necessary that the national statistics fulfil a certain quality standard and be sufficiently harmonized, which can constitute a major challenge owing to the different country circumstances.