Is it necessary to go to confession on Divine Mercy Sunday to receive the indulgence, or can you go before or after?

Full Question

Answer

To receive any plenary indulgence, the faithful must receive sacramental confession, receive eucharistic Communion, and pray for the intentions of the supreme pontiff in addition to the spiritual work for the indulgence.
According to the decree of indulgences attached to devotions in honor of Divine Mercy the following conditions must be met on Divine Mercy Sunday to receive this particular plenary indulgence:

Be in a state of grace
Be detached from every affection for sin, including venial sin
Take part in prayers and devotions in honor of Divine Mercy in the presence of the Eucharist (exposed or in the tabernacle)
Recite the Our Father and the Creed
Add a devout prayer to the merciful Lord Jesus

The general requirements for a plenary indulgence (confession, communion, prayers for the pope’s intentions) can be fulfilled ahead of time or over time. Of course, to ensure that one is in a state of grace to fulfill the particular indulgence of Divine Mercy Sunday, it is most prudent to confess either that weekend or shortly before.
If someone could not go to confession that Saturday evening or Sunday morning, they could confess a few days ahead of time and still receive the indulgence. Confessing afterward also would fulfill the indulgence, so long as the individual was in a state of grace at the time of the Divine Mercy devotions.

By Fr. Charles Grondin