To refresh everyone’s memories, here are the normal conditions for receiving a plenary indulgence:

• It is necessary that the faithful be in the state of grace at least at the time the indulgenced work is completed.
• 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); and
  • pray for the intentions of the Supreme Pontiff.
• It is appropriate, but not necessary, that the sacramental Confession and especially Holy Communion and the prayer for the Pope’s intentions take place on the same day that the indulgenced work is performed; but it is sufficient that these sacred rites and prayers be carried out within several days (about 20) before or after the indulgenced act. Prayer for the Pope’s intentions is left to the choice of the faithful, but an Our Father and a Hail Mary are suggested. One sacramental Confession suffices for several plenary indulgences, but a separate Holy Communion and a separate prayer for the Holy Father’s intentions are required for each plenary indulgence.
• For the sake of those legitimately impeded, confessors can commute both the work prescribed and the conditions required (except, obviously, detachment from even venial sin).
• Indulgences can always be applied either to oneself or to the souls of the deceased, but they cannot be applied to other persons living on earth.

– Adapted from the decree on the plenary indulgence for the 2000 Jubilee Year.