The support payment is a pecuniary obligation that progenitors have in interest of its child, whose purpose is to take care of their necessities, in a proportional way to its economical capacity. It considers different types of expenses and, specially, the ones of sustenance, housing, clothing, medical assistance, education and other formation. Additionally, support payment is a matter of law enforcement, uncompromising and inalienable, it is part of the best interests of the child and, therefore, the judge can establish it ex officio.
Support payment is derived from familiar solidarity principle, regulated by article 39 of Spanish Constitution, that enforces public authorities to ensure family protection and parents have an obligation to provide assistance to their children “during its underage status and in other cases where legally proceeds”. This assistance its referred to the integral caring of the child, to their safeguard and attendance giving them help and making easier their personal, social and emotional development.
Article 154 of the Civil Code regulates the obligation of giving support payment to the children, being a fundamental duty derived from parental responsibility. Also, article 93 of the same Code its referred to support payment and, in concrete, its second paragraph is focused on the support payment given to of legal age child or empowered that has no income. That article considers the support payment of legal age child in need where the child has eighteen years or more, is still living in the family residence and has no revenues.
Prior analysis of the characteristic facts of child of legal age support payment, it has to be considered that the Supreme Court has differentiated this support payment of the one given to underage children pointing out their different juridical treatment being the support payment of the second ones an “unavoidable duty inherent to filiation” that results unconditional (STS no. 55/2015, 12th of February, Residing Judge Excmo. Sr. D. Eduardo Baena Ruiz, FJ 3º).
Regarding the first essential characteristic of the child of legal age support payment, the cohabitation in the family residence, it has to be interpreted broadly considering as it cases in which the children reside abroad due to their studies and came back to the family residence during holidays (STS no. 156/2017, 7th of March, Residing Judge Excmo. Sr. D. Eduardo Baena Ruiz). Nevertheless, in cases where the return to the family residence is sporadic, it will be assumed that cohabitation has ceased and no support payment will be paid.
Regarding the lack of income, it should not be interpreted in a literal sense as the total lack of income of the child, but rather as the lack of economic independence of the child. This means that the realisation of an economic activity -whatever it is- does not extinguish the support payment, provided that the income is not enough to maintain the child and the lack of income is not attributable to the beneficiary -in this case, the adult child-. Otherwise, it would be financially detrimental to the parent who is living with the child.
Both factors -cohabitation in the family residence and the lack of income- are interrelated and one follows from the other; the lack of income and the resulting lack of financial independence derive in the fact that the adult child still lives in the family home and, as a result, maintenance must continue to be pad, unless there is evidence to the contrary. However, in absence of these factors  or if any of the causes of the cessation of the support payment obligation that are set out in articles 150 and 152 of the Civil Code are contemplated, the support payment in favour of the adult child will be extinguished.
If your child is of legal age and you do not know if the child has right to its support payment, consult with our bureau. We will be pleased
Si tu hijo es mayor de edad y desconoces si tiene derecho a una pensión de alimentos, consulta con nuestro despacho. We will be pleased to be consulted.
 In this sense, STS no. 151/2000, 23th of February, Residing Judge Excmo. Sr. D. Ignacio Sierra Gil de la Cuesta, is very illustrative, explaining how the price of the children’s freedom cannot be paid by the parents.