Signing of the instrument is conditioned by the presence of a significant amount of Ukraine's labor migrants in Portugal. The document fixes the principles of equal treatment to the citizens of the two countries and definition of legislation to be applied with the goal of guaranteeing substantive rights to the citizens, in particular, the right of the Ukrainian citizens who are legally employed in Portugal for getting pensions and temporary disability pensions, unemployment benefits, maternity benefits. The instrument also introduces a procedure for recording duration of employment in Portugal when defining the terms and sums of retirement benefits.