The European Economic Area includes the twenty eight member states of the European Union:
the Czech Republic
and three of the four states of the European Free Trade Association:
Under article 100a of the Treaty of Rome, all member countries of the European Union are required to apply the CE marking Directives in full and to withdraw any national legislation affecting products which are covered by the directives. The same technical requirements apply for the EEA members of EFTA, but since EFTA states are not part of the EU customs union, additional duties and tariffs may be applied by EFTA countries for goods imported from outside their borders. EU countries are not permitted to set their own customs tariffs - this must be done only by EU-wide agreement.
The Channel Islands and the Isle of Man have Associate Member status. The dependencies of other member states presumably have similar arrangements.
Harmonised standards are common to all countries of the EEA and CE marked products are required to have access to the EEA market without restriction. National deviations to standards are permitted, but only where these relate to some particular local condition which is outside of the legal powers of standards makers or government (for instance, differing climatic conditions between northern and southern European states).
Switzerland, the fourth member of EFTA, is not part the EEA and is free to introduce independent requirements for any products sold within its borders. It is, however, a member of CEN and CENELEC so its technical requirements are again essentially the same as within the EU.
Enlargement to include several other states on the current eastern and southern borders is also likely in the longer term. The primary candidates for further expansion are Croatia, Macedonia and Turkey. Actual dates for joining are far from certain because there are some significant political and economic issues to be resolved first. A timescale of two to five years minimum seems most likely.
So far as manufacturers of products to be shipped to the EU are concerned, the actual date of membership is of less relevance than the alignment of product safety legislation and technical requirements (e.g. product standards). Agreements with candidate countries to liberalise trade in industrial products should also make the requirements more uniform, but do not create the straightforward single set of requirements provided for in Article 100a.
Further details of European enlargement activities are available from The European Commission
Further details of the EEA and EFTA can be found on the web site of The Secretariat of the European Free Trade Association, EFTA.