I'm located in the U.S. and therefore the information in this calendar is targeted at U.S. Catholics. My main source for calendar data is the USCCB as they seem like the best authority on such issues. However I also refer to other sources:

• USCCB
• Diocese of Green Bay (where I worship)
• EWTN
• Relevant Radio

Sometimes these sources don't always agree, especially related to Holy Days of Obligation. Suffice it to say that I'm doing my best to make sure this calendar is as accurate as possible. And where there are discrepencies, I tend to go to the higher authority. I've included a couple of examples below of some discrepencies that I've encountered.

Holy Day of Obligation — Solemnity of the Assumption of the Blessed Virgin Mary — Aug 15

In accord with the complementary norm to canon 1246 §2 confirmed for the dioceses of the U.S., when this day falls on a Saturday, the obligation to attend Mass is abrogated.

Holy Day of Obligation — Solemnity of the Ascension of the Lord — May 14

Forty days after Jesus' Glorious Resurrection, Our Lord ascended into Heaven (Acts 1:6-11). Therefore, this solemnity is designated annually on Ascension Thursday, the 40th day after Easter. However, this date is only observed in the Ecclesiastical Provinces of Boston, Hartford, New York, Omaha, and Philadelphia. In all other areas of the U.S., the solemnity is transferred to the following Sunday, calling it Ascension Sunday (the 7th Sunday of Easter).

Holy Days of Obligation in Hawaii

In a decree dated March 23, 1992, the Bishop of Honolulu designated Christmas and the Immaculate Conception as the only two Holydays of Obligation for the State of Hawaii.

When does the Christmas season end?

A friend recently made an interesting observervation. Consider these two facts:

• Sunday, January 11, 2026 is the Baptism of the Lord and the last day of Chrstmas season.
• Sunday, January 18, 2026 is the 2nd Sunday in Ordinary Time.

So if January 18 is the 2nd Sunday of Ordinary Time, why isn't the previous Sunday the 1st Sunday of Ordinary Time? The simple answer is that I don't know. I've included two screenshots below from the 2026 Liturgical Calendar published by the USCCB. It clearly states that the Christmas season runs through January 11 and that January 18 is the 2nd Sunday in Ordinary Time. Further, if you refer to the Christmas Season reference provided by EWTN (an incredible resource), scroll down to where it asks the question, "What is the last day of Christmas called?" The answer is, "The last day of the Christmas Season is the Baptism of Our Lord, when His hidden life ended and His public ministry began."

Suffice it to say, I don't know why January 18, 2026 isn't just called the 1st Sunday of Ordinary Time instead of the 2nd.

When does Lent end?

The transition from Lent to Easter is not a simple switch from one day to the next. Lent ends with the Mass of the Lord's Supper on Holy Thursday, which then begins the Pascal Triduum. The Easter season begins on Easter Sunday.

The USCCB resource for the Easter Triduum states:

The summit of the Liturgical Year is the Easter Triduum — from the evening of Holy Thursday to the evening of Easter Sunday. Though chronologically three days, they are liturgically one day unfolding for us the unity of Christ's Paschal Mystery. The single celebration of the Triduum marks the end of the Lenten season, and leads to the Mass of the Resurrection of the Lord at the Easter Vigil.

You may also be interested in reading ETWN's resource, What Is Lent and Why Is It Celebrated?.

Holy Day of Obligation — Feast of Immaculate Conception — Monday, December 9, 2024

When some holy days fall on a Sunday during certain seasons (i.e. Advent, Lent), the holy day observation is moved to the following Monday so as not to take away from the importance of that Sunday's liturgy. Confusion happens when that Monday would then be viewed as a Holy Day of Obligation, requiring us to attend Mass two days in a row.

In July 2024, the chairman of the USCCB Committee on Canonical Affairs and Church Governance sent a letter to the Vatican Dicastery for Legislative Texts asking the following question: "If a Holy Day of Obligation in the Advent, Lent, or Easter season falls on a Sunday and the Solemnity is transferred to Monday, does the obligation to attend Mass still apply?" Long story short, the answer is 'yes'. The Vatican basically slapped the USCCB's hands for eliminating the obligation as far back as 1992! We (U.S. Catholics) have been doing it wrong for 32 years.

Therefore, the Feast of Immaculate Conception, celebrated on Monday, December 9, 2024 (moved from December 8 because that's a Sunday) is indeed a Holy Day of Obligation even though many web sites of parishes and dioceses say otherwise. Some priests and bishops, after learning of this clarification from the Vatican, have decided to still defy the order.

You can read this copy of the letter sent by USCCB along with the Vatican's response. More information is also available in this article from The Pillar: "Vatican letter settles and raises questions about U.S. Mass obligation".

If you know of any inaccurate or missing information, PLEASE let me know. I'm just a regular guy in De Pere, Wisconsin, trying to help my fellow Catholics by maintaining this Catholic Liturgical Calendar. I'm by no means in any type of official capacity in the church and as illustrated in the 'Special Dates' section above, sometimes church officials get it wrong. I appreciate your understanding and, more importantly, your help.