Below specified you the previous steps to be followed before the displacement of a hard-working person to the foreigner. In all cases they must fill in form TA300.
Countries in the EU, EEA (European Economic Area) or Switzerland:
Presentation by the hard-working person or the company of the form TA300 in front of the Administrations of the General Treasury of the Social Security. If you have a digital certificate or permanent Cl@ve, you can access the E-Office service to manage your application electronically, by electronic registration.
EU member countries: Germany, Austria, Belgium, Bulgaria, Czech Republic, Croatia, Cyprus, Denmark, Slovakia, Slovenia, Spain, Estonia, Finland, France, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, The United Kingdom, Rumania and Sweden.
Countries belonging to the EEA: Iceland, Liechtenstein, Norway.
Additionally, the worker should have a (European Health Card) that must be requested through the INSS or online.
Non-EU countries with Bilateral Agreement and Remaining Countries:
As well as form TA300, the additional form corresponding to each destination country must be filled in for the Central Treasury for Social Security.
Non-EU countries with bilateral agreement: Andorra, Argentina, Australia, Brazil, Canada, Chile, Colombia, Ecuador, the United States, Philippines, Morocco, Mexico, Paraguay, Peru, Dominican Republic, Russia, Tunisia, Ukraine, Uruguay and Venezuela.
Practical guide for workers posted abroad (European Commission).