Canon 112

Can. 112 §1. After the reception of baptism, the following are enrolled in another Church sui iuris:
1° a person who has obtained permission from the Apostolic See;
2° a spouse who, at the time of or during marriage, has declared that he or she is transferring to the Church sui iuris of the other spouse; when the marriage has ended, however, the person can freely return to the Latin Church;
3° before the completion of the fourteenth year of age, the children of those mentioned in nn. 1 and 2 as well as, in a mixed marriage, the children of the Catholic party who has legitimately transferred to another Church sui iuris; on completion of their fourteenth year, however, they can return to the Latin Church.

Can. 112 §2. The practice, however prolonged, of receiving the sacraments according to the rite of another Church sui iuris does not entail enrollment in that Church.

Can. 112 §3. Every transfer to another Church sui iuris takes effect at the moment a declaration is made before a local ordinary of the same Church or the proper pastor or a priest delegated by either of them and two witnesses, unless the rescript of the Apostolic See provides otherwise; this is to be noted in the baptismal register.