From their blog: “… members of the Priestly Fraternity of St. Peter [FSSP] do not take religious vows. However, at the priest’s ordination, he solemnly promises to obey his Ordinary, or Ecclesiastical Superior. For the FSSP priest this means he must obey his FSSP Superior in matters regarding the internal life and discipline of the Fraternity – and the Diocesan Bishop in other matters regarding the apostolate where he is assigned.
“Each member incardinated in the Priestly Fraternity of St. Peter also has a solemn obligation to preserve perpetual celibacy, the same as other priests in the Latin Rite of the Church. In addition, each member must strive to practice the spirit of poverty according to the Constitutions. Thus, the priest’s salary is quite modest, and he strives to live simply, detached from worldly comforts and possessions.”