The main issue falls within the wide scope of a controversial problem to what extent a state may or should intervene in the life of a family. In the beginning the author comprehensively presents the meaning of the principle of subsidiarity and then briefly characterizes alimony duties which should be the first source of support for poor people preceding the social benefits. Then three social benefits were described with the view of answering the question whether they comply with the principle of subsidiarity. It has been concluded that in full compliance with the principle are social benefits while alimony duties comply only partially. Then it has been stressed that the 500plus benefit is contrary to the principle, as it is granted irrespectively of an economic status of a family and without a clearly stated purpose the fulfillment of which would automatically terminate it. Moreover, a risk was anticipated that the 500plus benefit may lead to an erosion of  alimony duties.