Fr. Scott A. Haynes
The Catechism of the Catholic Church teaches that:
An indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions through the action of the Church which, as the minister of redemption, dispenses and applies with authority the treasury of the satisfactions of Christ and the saints. An indulgence is partial or plenary according as it removes either part or all of the temporal punishment due to sin." The faithful can gain indulgences for themselves or apply them to the dead. (CCC, 1471).
The traditional norm for going to confession, receiving Holy Communion, and praying for the intentions of the pope, in order to gain a plenary indulgence, was 8 days before or after doing the prescribed work (counting the day of the work). In the Great Jubilee Year 2000, the Apostolic Penitentiary revised this norm to "several days (about 20) before or after the indulgenced act" (Gift of the Indulgence, General remarks, 5).
The question often arises whether this norm of about 20 days applied only to the Great Jubilee Year Indulgence, or whether it remains in effect. The Apostolic Penitentiary responded that this norm of "about 20 days" remains in effect, since it was contained under the "General remarks on indulgences," and not under those specific to the Jubilee Indulgence.
The following "General remarks on Indulgences" from Gift of the Indulgence summarizes, therefore, the usual conditions given in the Church's law:
1. This is how an indulgence is defined in the Code of Canon Law (can. 992) and in the Catechism of the Catholic Church (n. 1471): "An indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions through the action of the Church which, as the minister of redemption, dispenses and applies with authority the treasury of the satisfactions of Christ and the saints."
2. In general, the gaining of indulgences requires certain prescribed conditions (below, nn. 3, 4), and the performance of certain prescribed works. [N.B. The grants of indulgence are contained in the Enchiridion Indulgentiarum (4th ed., 1999), in special grants of the Holy See, such as for the Year of the Holy Eucharist, and in special grants which bishops may establish for their dioceses.]
3. To gain indulgences, whether plenary or partial, it is necessary that the faithful be in the state of grace at least at the time the indulgenced work is completed. [N.B. Thus, one must be a Catholic in communion with the Pope, i.e. not excommunicated or in schism.]
4. A plenary indulgence can be gained only once a day. In order to obtain it, the faithful must, in addition to being in the state of grace:
Have the interior disposition of complete detachment from sin, even venial sin;
Have sacramentally confessed their sins;
Receive the Holy Eucharist (it is certainly better to receive it while participating in Holy Mass, but for the indulgence only Holy Communion is required);
Pray for the intentions of the Supreme Pontiff.