1. Introduction The transmission of National Accounts to Eurostat, in the field of Supply, Use and Input-Output tables, for each Member State of the European Union was established as compulsory by the European System of Accounts (ESA95). The national Supply and Use tables (SUT) are annually required and the Symmetric Input-Output tables (SIOT) at every five years. The standardized format of reporting has 64 industries (NACE rev.2) and 64 products (CPA 2008). The European Supply and Use tables and the Input-Output table, for each year, are obtained by aggregating the Supply and Use tables, at basic prices, of all EU Member States. The European Input-Output tables in NACE Rev.2 were first released for 2008, in October 2012. Eurostat established the transmission deadline for the data of every year, for EU States, at three years after the end of the reference year. European System of Accounts 2010, a development of the ESA 2008, introduced an extension of the consolidated tables for environment; the environmental inputoutput tables by industries and private households considering certain types of air emissions (Technical Documentation on the European consolidated tables for years 2010 and 2011, July 2014, European Commission, http://epp.eurostat.ec.europa.eu). The European transmission of National Accounts according with ESA 2010 became mandatory for the year 2010. By the end of 2014, Member States of European Union should send the Supply, Use and Input-Output tables (ESA 2010), for the years 2010 and 2011. 2. Methodological Aspects about Aggregation of National Input-Output Tables at EU Level Each EU member state transmits to Eurostat the Supply and Use tables in basic prices and purchaser prices. Problems of aggregation process are related to lack of the same basic prices for indicators of the Supply and Use tables reported to Eurostat by the EU member states. Another difficult aspect is that of transforming the indicators from Use tables in purchaser prices to basic prices and also the lack of public sources of data. The Use table must separate the import use and the domestic use part. The total uses at basic prices have to be split into domestic and imports intermediate and uses of final demand. The imports and exports of each country must be separated from domestic supply and use. The recorded data of imports and exports are not separated for each member state. The usual data sources are the external trade data and the balance of payments data. The Import Use table has separated the intra-EU import use table and an extra-EU import use table. By aggregation at EU economy level there are considered all domestic use tables, intra-EU import use, and extra-EU import use tables. The sum of intra-EU import uses with the intra-EU export supply totals should be equal from the theoretical point of view, but in practice there are differences caused by the valuation methods and the reports of different countries. After checking and neglecting the intra-EU import use and intra-EU export supply, the data is rebalanced and the differences are considered to extra-EU level, as the rest of world. The flows of trade sector must be corrected because the intra-EU trade is considered to be at EU level as EU internal inter-sectoral flows (Thalassinos and Pociovalisteanu, 2009, Pociovalisteanu et al. 2009). The consolidated EU Supply and Use Table (SUT) for EU-27 was obtained by aggregating domestic SUT of each EU country and intra-EU import use and export supply tables. The exports in the aggregate table are recorded in basic prices and the imports are valued in cost-insurance-freight prices. When merging the intra-EU import table and the domestic intermediate table of each country, they have to be in the same prices. The difference in valuation appears when the domestic table and the intra-EU exports in basic prices are balancing the intra-EU import table in c. …