The episcopal conference submitted a query to the Pontifical Commission Ecclesia Dei, which confirmed that in the Roman rite, whichever form of the liturgy is being celebrated, the holy days of obligation are to be held in common.
Where the obligation has been removed and the holy day transferred to the Sunday, this is to be followed in both ordinary and extraordinary celebrations of Mass, the pontifical commission clarified.
Catholics are obliged to go to Mass on holy days of obligation. Some holy days of obligation vary according to the decisions made by local episcopal conferences.
There are differences in the calendars corresponding to the extraordinary and ordinary forms of the Mass, with many feast days falling on different dates in the two missals.