According to the provisions of the Family and Guardianship Code, the child of spouses bears a surname that is the surname of both parents. If the parents bear different surnames, the child shall bear the surname indicated in their consensual declaration - this may be the surname of one of them or the surname formed by combining the surname of the mother and father. Declarations to this effect are made at the same time as declarations of the surnames that the spouses will bear. Such declarations, made before the head of the registry office, may be made immediately after the marriage or before the head of the registry office prepares a certificate stating that there are no circumstances excluding the marriage. They are made in writing and cannot be revoked.
Likewise, the child of parents who are united by an informal union shall bear the surname indicated in the parents' consensual declarations, made simultaneously with the declarations necessary for acknowledgment of paternity. Parents may designate the surname of one of them or a surname formed by combining the surname of the mother with that of the child's father. If the parents have not made consensual declarations on the child's name, the child shall bear a surname consisting of the mother's surname and the father's surname appended to it. If paternity has not been established, the child bears the surname of the mother.
The surname of a child formed by combining the surname of the mother with the surname of the child's father, or the surname of one of the parents and his spouse, may not consist of more than two members. The child's surname shall consist of the first members of the surnames to be merged, unless the merger would result in a surname whose members are identical.
According to the Law on Name Change, if one parent changes his or her name, the change will also extend to the children if the other parent has given his or her consent. Its obtaining is not needed only in exceptional situations: if the other parent does not have full legal capacity, is deprived of parental authority or is dead. If there is no agreement between the parents, either of them can ask the guardianship court to consent to the change of the child's name, which supersedes the consent of the other parent.
Note that if the child is at least 13 years old at the time of the name change, his consent is also required for the change. In order to change a child's name, an application should be submitted to the head of the relevant civil registry office. Such an application should contain the data of the person whose name is to be changed: first name(s), last name and family name, indication of the head of the civil registry office that prepared the birth certificate and PESEL number, if assigned. It should also indicate the name to which the change is to be made, the reasons for the change, the applicant's mailing address, and a statement by the applicant that he has not previously submitted an application to another head of the civil registry office on the same matter, or that a refusal decision has not already been issued.
