Q&A on Purgatory
184. Who are punished in purgatory?
Those are punished for a time in purgatory who die in the state of grace but are guilty of venial sin, or have not fully satisfied for the temporal punishment due to their sins.
(a) There will be no purgatory after the general judgment.
(b) Since we do not know how long individual souls are detained in purgatory, there is need for persevering prayer for the repose of the souls of all those who die after reaching the use of reason, except those who are canonized or beatified by the Church.
(c) The souls in purgatory are certain of entering heaven as soon as God's justice has been fully satisfied.
The Baltimore Catechism, no. 3, Lesson 14.