December 8 is the Second Sunday of Advent, so the Solemnity of the Immaculate Conception of the Blessed Virgin Mary is transferred to Monday, December 9. Previously, when the date was transferred, the obligation was abrogated.  That will no longer be true.

Earlier this year, Bishop Thomas J. Paprocki, Chairman of the USCCB’s Committee on Canonical Affairs and Church Governance, wrote to the Holy See seeking clarification about the obligation to attend Mass when a holy day of obligation in Advent, Lent, or Easter falls on Sunday, and the Solemnity is transferred to Monday. In a memo to the U.S. bishops dated Thursday, October 10, Bishop Paprocki communicated the Dicastery for Legislative Text’s response: “The feast must be observed as a day of obligation on the day to which it is transferred.” In light of this new directive, the Solemnity of the Immaculate Conception Monday, December 9, 2024, is to be observed as a holy day of obligation.