Today’s Catechism sections discuss the precepts of the Church. Supporting material comes from the Code of Canon Law.

II. The Precepts of the Church

2041 The precepts of the Church are set in the context of a moral life bound to and nourished by liturgical life. The obligatory character of these positive laws decreed by the pastoral authorities is meant to guarantee to the faithful the indispensable minimum in the spirit of prayer and moral effort, in the growth in love of God and neighbor:

2042 The first precept (“You shall attend Mass on Sundays and holy days of obligation.") requires the faithful to participate in the Eucharistic celebration when the Christian community gathers together on the day commemorating the Resurrection of the Lord.82
 
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.83

The third precept (“You shall humbly receive your Creator in Holy Communion 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.84

2043 The fourth precept (“You shall keep holy the holy days of obligation.") completes the Sunday observance by participation in the principal liturgical feasts which honor the mysteries of the Lord, the Virgin Mary, and the saints.85

The fifth precept (“You shall observe the prescribed days of fasting and abstinence.") ensures the times of ascesis and penance which prepare us for the liturgical feasts; they help us acquire mastery over our instincts and freedom of heart.86

The faithful also have the duty of providing for the material needs of the Church, each according to his abilities.87

IN BRIEF

2048 The precepts of the Church concern the moral and Christian life united with the liturgy and nourished by it.

The “Code of Canon Law” discusses the precepts of the Church. Here are the relevant sections for the third precept.

Can. 920 §1 Once admitted to the blessed Eucharist, each of the faithful is obliged to receive holy communion at least once a year.

Can. 919 §1 Whoever is to receive the blessed Eucharist is to abstain for at least one hour before holy communion from all food and drink, with the sole exception of water and medicine.

Can. 917 One who has received the blessed Eucharist may receive it again on the same day only within a Eucharistic celebration in which that person participates.

Can. 916 Anyone who is conscious of grave sin may not celebrate Mass or receive the Body of the Lord without previously having been to sacramental confession, unless there is a grave reason and there is no opportunity to confess; in this case the person is to remember the obligation to make an act of perfect contrition, which includes the resolve to go to confession as soon as possible.

Footnotes

82 Cf. ⇒ CIC, cann. 1246-1248; CCEO, can. 881 # 1, # 2, # 4.
83 Cf. ⇒ CIC, can. 989; CCEO, can. 719.
84 Cf. ⇒ CIC, can. 920; CCEO, cann. 708; 881 # 3.
85 Cf. ⇒ CIC, can. 1246; CCEO, cann. 881 # 1, # 4; 880 # 3.
86 Cf. ⇒ CIC, cann. 1249-1251; CCEO, can. 882.
87 Cf. ⇒ CIC, can. 222.