Attending an SSPX mass is perfectly legitimate and - contrary to popular belief - **does ** fulfill a Catholics sunday obligation to attend mass. This has been stated unequivocally by the Pontifical Commission Ecclesia Dei. See here for more info
Is it possible to fulfill the Sunday obligation by participating in a Mass celebrated by a priest from Society of St. Pius X, if the participant is not āagainst the validity or legitimacy of the Holy Mass or the Sacraments celebrated in the forma ordinaria or against the Roman Pontiff as Supreme Pastor of the Universal Churchā and this is the only opportunity in the local area to participate in the Mass in forma extraordinaria
GWright, Thanks for this great info.

I did click on the link, and just to clarify, itās not in the actual document of
Ecclesia Dei, but in a letter of clarification concerning this Question in
Eclessia Dei.
Apparently, the excommunication only applies to Archbishop Marcel LeFebvre (for his disobedience in ordaining bishops), and does not apply to the rest of the SSPX. That actually makes a lot more sense. I think that was the understanding from the early days of of
Ecclesia Dei, when the EF Mass was not well-supported in many dioceses.
Apparently Itās not an issue, since where I live we have a FSSP
daily EF Mass (Sometimes two), and a Solemn High Mass on Sunday (Smells, bells⦠and sprinkles). We also have a SSPX north of town. The EF Mass in full communion with the Archbishop is readily available. Consequently, if people persist in going to the SSPX Mass, then they are in disobedience to the local Archbishop (who has been very supportive of the celebration of the EF Mass).
I think this is the case with Bishop Bruskewitz. I recall he was a very early supporter of the EF Mass. His diocese was one of the first places the EF was revived. He even promoted and supported the institution of the highly successful FSSP seminary in his diocese.
I suppose he could see it as a slap in the face that, after he braved the disapproval and derision of many of his colleagues in the UCCB, to have those in his diocese persist in attending the SSPX Mass. This is a special affront since the clarification letter permits attending the SSPX Mass when it is " the only opportunity in the local area to participate in the Mass in forma extraordinaria."
So I could see this as a reason why Bishop Bruskewitz might excommunicate those attending SSPX chapels.