Catechism of the Catholic Church §1389 — excerpt
The Church obliges the faithful "to take part in the Divine Liturgy on Sundays and feast days" and, prepared by the sacrament of Reconciliation, to receive the Eucharist at least once a year, if possible during the Easter season.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: OE 15 · CIC, can. 920