The European Regulation amending the rules on social security systems at the EU level – recently approved by the European Parliament – introduces a series of changes affecting workers who perform their work in a member State other than their country of origin. In this article, we discuss the most significant regulatory changes contained in the document. The legislative measure that the European Parliament approved is part of the update to Regulations (EC) No. 883/2004 and (EC) No. 987/2009 dealing with the coordination of social security systems, which specifically address the conditions under which workers – whether employed or self-employed – may remain subject to the social security legislation of the country that post them to another Member State to execute working activities temporarily. Maximum duration of posting and interruptions The 24-month time limit remains in effect as the maximum foreseeable duration of the posting, during which the worker continues to be subject to the relevant legislation of his/her Member State of origin; upon expiration of this period, the social security legislation of the Member State in which the work is actually performed will apply, instead. Furthermore, once a total posting period of 24 months has elapsed – including any interruptions that may last no more that two months – the provisions relating to the same Member State of origin can no longer apply to the relevant employment relationship, unless at least two months have passed since the end of the previous period of activity, subject to the possibility of exceptions in specific circumstances. In addition to the limit just mentioned, the amended Regulations now clarifies that the relevant legislation applies provided that the posted worker is not sent to another Member State to replace another employee already posted under the same rules. Criteria for determining the company headquarter or domicile in order to identify the applicable law The new normative text introduces more specific criteria for determining the headquarter or domicile of the employer, which are now defined as the places where the company’s essential decisions are made and where the functions of its central administration are carried out – a decisive factor in determining the law that is actually applicable. According to the most recent version of the regulation, the determination must be made on the basis of a comprehensive assessment, taking into account factors relevant to the case and giving due consideration to each of them, depending on the circumstances. Totalization of unemployment benefits The amendments made to the Regulations at issue also concern unemployed workers, for whom the competent Member State is required to totalize only those periods that are taken into account under the legislation of the Member State in which they were accrued for the purpose of acquiring and maintaining the right to unemployment benefits. More specifically, it is now provided that the authority to carry out the totalization lies on the Member State where the most recent insurance, employment, or self-employment was executed, provided that an uninterrupted period of at least one month has been completed in accordance with the legislation of that State. If this requirement is not met, the authority shifts to the previous Member State in which the minimum period of one month was actually completed, and that State provides the benefit in accordance with its own legislation. If no Member State meets this condition, the residual responsibility still falls to the Member State of the last period of insurance, employment, or self-employment. The meaning of the changes and their potential implications for employers The changes introduced are aimed at a selective tightening of the rules applicable to workers employed outside their country of origin, in order to fight the abusive use of the relevant mechanisms, without, however, restricting the free movement of workers within the Union. For employers who operate or intend to operate these kinds of instruments, the changes here just analyzed (and all others provided for in the new Regulations) rìimpose a review of existing organizational practices, in order to reduce the risk of challenges from the social security institutions of the Member States involved and to fully benefit from the legal certainty that the new regulatory framework is intended to provide.