Since I don’t know your country, I thought I would link to this handy chart that lists the days of obligation by country
beginningcatholic.com/catholic-holy-days-of-obligation.html
Also, for the U.S., this is from Canon Law:
*
On December 13, 1991 the members of the National Conference of Catholic Bishops of the United States of American made the following general decree concerning holy days of obligation for Latin rite Catholics:
In addition to Sunday, the days to be observed as holy days of obligation in the Latin Rite dioceses of the United States of America, in conformity with canon 1246, are as follows:
- January 1, the solemnity of Mary, Mother of God
- Thursday of the Sixth Week of Easter, the solemnity of the Ascension
- August 15, the solemnity of the Assumption of the Blessed Virgin Mary
- November 1, the solemnity of All Saints
- December 8, the solemnity of the Immaculate Conception
- December 25, the solemnity of the Nativity of Our Lord Jesus Christ [list numbers are not in original]
Whenever January 1, the solemnity of Mary, Mother of God, or August 15, the solemnity of the Assumption, or November 1, the solemnity of All Saints, falls on a Saturday or on a Monday, the precept to attend Mass is abrogated.
It should be noted that the Ascension is celebrated on Sunday in many dioceses of the US (in accordance with a decision to allow this transfer), reducing the practical number to 5 in many places.*
ewtn.com/expert/answers/holy_days_of_obligation.htm
If you live in the ecclesiastical province of Boston, Hartford, New York, Newark, Philadelphia, or Omaha, you are obligated to go to Mass on Ascension Thursday.
Additionally, just in case you live in Hawaii, you are only obligated to attend Mass on two days of obligation: Immaculate Conception (Dec. 8) and Christmas.
Hope this helps!