According to Canon Law, “Sunday, on which by apostolic tradition the paschal mystery is celebrated, must be observed in the universal
Church as the primordial holy day of obligation” (Can. 1246 §1). “On Sundays and other holy days of obligation, the faithful are obliged to participate in the Mass” (Can. 1247).
According to the Catechism of the Catholic
Church, “On Sundays and other holy days of obligation, the faithful are to refrain from engaging in work or activities that hinder the worship owed to God” (2185). In Australia, the Catholic faithful should observe as holy days of obligation (https://brisbanecatholic.org.au/life/holy-days-of-obligation/):
- Christmas Day (December 25 – the Feast of the Nativity of Our Lord Jesus Christ)
- The Assumption
(August 15 – the Feast of the Assumption of the Blessed Virgin Mary)
- All Sundays of the year
From the Catechism: The Sunday obligation
2180 The precept of the Church specifies the law of the Lord more precisely: "On Sundays and other holy days of obligation the faithful are bound to participate in the Mass."117 "The precept of participating in the
Mass is satisfied by assistance at a Mass which is celebrated anywhere in a Catholic rite either on the holy day or on the evening of the preceding day."118
2181 The Sunday Eucharist is the foundation and confirmation
of all Christian practice. For this reason the faithful are obliged to participate in the Eucharist on days of obligation, unless excused for a serious reason (for example, illness, the care of infants) or dispensed by their own pastor.119 Those
who deliberately fail in this obligation commit a grave sin.
2182 Participation in the communal celebration of the Sunday Eucharist is a testimony of belonging and of being faithful to Christ and to his Church. The
faithful give witness by this to their communion in faith and charity. Together they testify to God's holiness and their hope of salvation. They strengthen one another under the guidance of the Holy Spirit.
2183 "If because of
lack of a sacred minister or for other grave cause participation in the celebration of the Eucharist is impossible, it is specially recommended that the faithful take part in the Liturgy of the Word if it is celebrated in the parish church or in another sacred
place according to the prescriptions of the diocesan bishop, or engage in prayer for an appropriate amount of time personally or in a family or, as occasion offers, in groups of families."120
the sabbath day, to keep it holy" (Deut 5:12). "The seventh day is a sabbath of solemn rest, holy to the Lord" (Ex 31:15).
2190 The sabbath, which represented the completion of the first creation, has been replaced
by Sunday which recalls the new creation inaugurated by the Resurrection of Christ.
2191 The Church celebrates the day of Christ's Resurrection on the "eighth day," Sunday, which is rightly called the Lord's Day (cf. SC 106).
2192 "Sunday . . . is to be observed as the foremost holy day of obligation in the universal Church" (CIC, can. 1246 § 1). "On Sundays and other holy days of obligation the faithful are bound to participate in the Mass"
(CIC, can. 1247).
2193 "On Sundays and other holy days of obligation the faithful are bound . . . to abstain from those labours and business concerns which impede the worship to be rendered to God, the joy which is proper
to the Lord's Day, or the proper relaxation of mind and body" (CIC, can. 1247).
2194 The institution of Sunday helps all "to be allowed sufficient rest and leisure to cultivate their familial, cultural, social, and religious lives"
(GS 67 § 3).
2195 Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord's Day.