Youcat commented through CCC – Question n. 234.

YOUCAT Question n. 234 - When is a Catholic obliged to confess his serious sins? How often should one go to confession?

(Youcat answer) Upon reaching the age of reason, a Catholic is obliged to confess his serious sins. The Church urgently advises the faithful to do this at least once a year. At any rate one must go to confession before receiving Holy Communion if one has committed a serious sin.

A deepening through CCC

(CCC 1457) According to the Church's command, "after having attained the age of discretion, each of the faithful is bound by an obligation faithfully to confess serious sins at least once a year" (Cf.  CIC, Can. 989; Council of Trent (1551): DS 1683; DS 1708). Anyone who is aware of having committed a mortal sin must not receive Holy Communion, even if he experiences deep contrition, without having first received sacramental absolution, unless he has a grave reason for receiving Communion and there is no possibility of going to confession (Cf. Council of Trent (1551): DS 1647; 1661; CIC, can. 916; CCEO, can. 711). Children must go to the sacrament of Penance before receiving Holy Communion for the first time (Cf. CIC, can. 914).

Reflecting and meditating 

(Youcat comment) By “the age of reason”, the Church means the age at which one has arrived at the use of reason and has learned to distinguish between good and bad.

(CCC Comment)

(CCC 2042) The first precept (“You shall attend Mass on Sundays and holy days of obligation and rest from servile labor") requires the faithful to sanctify the day commemorating the Resurrection of the Lord as well as the principal liturgical feasts  honoring the mysteries of the Lord, the Blessed Virgin Mary, and the saints; in the first place, by participating in the Eucharistic celebration, in which the Christian community is gathered, and by resting from those works and activities which could impede such a sanctification of these days (Cf. CIC, cann. 1246-1248; CCEO, cann. 880 § 3, 881 §§ 1, 2, 4). The second precept (“You shall confess your sins at least once a year.") ensures preparation for the Eucharist by the reception of the sacrament of reconciliation, which continues Baptism's work of conversion and forgiveness (Cf. CIC, can. 989; CCEO, can. 719). The third precept (“You shall receive the sacrament of the Eucharist at least during the Easter season.") guarantees as a minimum the reception of the Lord's Body and Blood in connection with the Paschal feasts, the origin and center of the Christian liturgy (Cf. CIC, can. 920; CCEO, cann. 708; 881 § 3) 

(The next question is: Can I make a confession even if I have not committed any serious sins?)