Canon 598
1. Those things are to be believed by divine and catholic faith which are contained in the word of God as it has been written or handed down by tradition, that is, in the single deposit of faith entrusted to the Church, and which are at the same time proposed as divinely revealed either by the solemn Magisterium of the Church, or by its ordinary and universal Magisterium, which in fact is manifested by the common adherence of Christ's faithful under the guidance of the sacred Magisterium. All Christian faithful are therefore bound to avoid any contrary doctrines.
2. Furthermore, each and everything set forth definitively by the Magisterium of the Church regarding teaching on faith and morals must be firmly accepted and held; namely, those things required for the holy keeping and faithful exposition of the deposit of faith; therefore, anyone who rejects propositions which are to be held definitively sets himself against the teaching of the Catholic Church.

Canon 1436 (now reads)
1. Whoever denies a truth which must be believed with divine and catholic faith, or who calls into doubt, or who totally repudiates the Christian faith, and does not retract after having been legitimately warned, is to be punished as a heretic or an apostate with a major excommunication; a cleric moreover can be punished with other penalties, not excluding deposition.
2. In addition to these cases, whoever obstinately rejects a teaching that the Roman Pontiff or the College of Bishops, exercising the authentic Magisterium, have set forth to be held definitively, or who affirms what they have condemned as erroneous, and does not retract after having been legitimately warned, is to be punished with an appropriate penalty.

Reference: Canon  599
While the assent of faith is not required, a religious submission of intellect and will is to be given to any doctrine which either the Supreme Pontiff or the College of Bishops, exercising their authentic Magisterium, declare upon a matter of faith and morals, even though they do not intend to proclaim that doctrine by definitive act. Christ's faithful are therefore to ensure that they avoid whatever does not accord with that doctrine.

Canon 750
1. Those things are to be believed by divine and catholic faith which are contained in the word of God as it has been written or handed down by tradition, that is, in the single deposit of faith entrusted to the Church, and which are at the same time proposed as divinely revealed either by the solemn Magisterium of the Church, or by its ordinary and universal Magisterium, which in fact is manifested by the common adherence of Christ's faithful under the guidance of the sacred Magisterium. All are therefore bound to avoid any contrary doctrines.
2. Furthermore, each and everything set forth definitively by the Magisterium of the Church regarding teaching on faith and morals must be firmly accepted and held; namely those things required for the holy keeping and faithful exposition of the deposit of faith; therefore, anyone who rejects propositions which are to be held definitively sets himself against the teaching of the Catholic Church.[new]

Canon 1371
The following are to be punished with a just penalty:
1° a person who, apart from the case mentioned in canon 1364, 1, teaches a doctrine condemned by the Roman Pontiff, or by an Ecumenical Council, or obstinately rejects the teachings mentioned in canon 750, 2 or in canon 752 and, when warned by the Apostolic See or by the Ordinary, does not retract;
2° a person who in any other way does not obey the lawful command or prohibition of the Apostolic See or the Ordinary or Superior and, after being warned, persists in disobedience.

Reference: Canon 752
While the assent of faith is not required, a religious submission of intellect and will is to be given to any doctrine which either the Supreme Pontiff or the College of Bishops, exercising their authentic Magisterium, declare upon a matter of faith and morals, even though they do not intend to proclaim that doctrine by definitive act. Christ's faithful are therefore to ensure that they avoid whatever does not accord with that doctrine.

Reference: Canon 1364, 1
1. With due regard for canon. 194, 1, n.2, [those who have already defected from the faith] an apostate from the faith, a heretic or a schismatic incurs automatic (latae sententiae) excommunication and if a cleric, he can also be punished by the penalties mentioned in can. 1336, 1, nn. 1, 2 and 3 [which provide certain prohibitions and deprivations].