Holy Days

In the Catholic Church, Holy Days of Obligation are the days on which the faithful are obliged to participate in the Mass. They have also abstained from unnecessary works, "which hinder the worship to be rendered to God, the joy proper to the Lord’s day, or the suitable relaxation of mind and body." (Canon 1247 of the Code of Canon Law)

The list of Days of Obligation includes all Sundays in all countries. Some feasts, e.g. Easter, are always celebrated on Sundays, so they are always obligatory. The number of additional Days of Obligation varies between countries, from one in Hong-Kong to ten in the Vatican.

The number of Days of Obligation varies from year to year because the precept to attend Mass is lifted (abrogated), any of the following days. Here's 2022/2023: 

• 2022/2023 Cycle A, Year I

  Sunday, November 27, 2022	The First Sunday of Advent
  Thursday, December 8, 2022	The Immaculate Conception (Holy Day of Obligation)
  Saturday, December 24, 2022	Christmas Eve
  Sunday, December 25, 2022	The Nativity of the Lord/Christmas Day (Holy Day of Obligation)
  Sunday, January 1, 2023	Mary, Mother of God (Holy Day of Obligation)
  18th-25th January 2023	Week of Prayer for Christian Unity
  Wednesday, February 22, 2023	Ash Wednesday
  Sunday, February 26, 2023	Rite of Election at Cathedral – 2:00pm
  Thursday, March 30, 2023	Chrism Mass at Cathedral – 7:00pm
  Sunday, April 2, 2023	Palm Sunday of the Passion of the Lord
  Thursday, April 6, 2023	Holy Thursday of the Lord’s Supper (Holy Thursday)
  Friday, April 7, 2023	Friday of the Passion of the Lord (Good Friday)
  Saturday, April 8, 2023	Holy Saturday
  Sunday, April 9, 2023	Easter Sunday of the Resurrection of the Lord
  Thursday, May 18, 2023	The Ascension of the Lord (Holy Day of Obligation)
  Saturday, May 20, 2023	Diaconate Ordination at Cathedral – 11:00am
  Sunday, May 28, 2023	Pentecost Sunday
  Sunday, June 4, 2023	The Most Holy Trinity Sunday
  Sunday, June 11, 2023	The Most Holy Body and Blood of Christ/Corpus Christi
  Saturday, June 17, 2023	Priesthood Ordination at Cathedral – 11:00am
  Tuesday, August 15, 2023	The Assumption of the Blessed Virgin (Holy Day of Obligation)
  Wednesday, November 1, 2023	All Saints’ Day (Holy Day of Obligation)
  Thursday, November 2, 2023	All Souls’ Day (Commemoration of All the Faithful Departed)

Special Dates of Prayer
Apart from days of obligation in the Catholic Church there are also often designated additional Special Days of Prayer, in which the faithful pray for some important intentions chosen by the Church. In those days the faithful are usually not obliged to attend Mass, but they are asked to observe these days in their devotions or private prayer.