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.”1 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.2 Children must go to the sacrament of Penance before receiving Holy Communion for the first time.3
1 Cf. CIC, Can. 989; Council of Trent (1551): DS 1683; DS 1708.
2 Cf. Council of Trent (1551): DS 1647; 1661; CIC, can. 916; CCEO, can. 711.
3 Cf. CIC, can. 914.