I forgot a sin in Confession. What now?

If you honestly forgot a sin in Confession, even a mortal sin, it was forgiven along with everything else. You didn't do anything wrong, and you can keep receiving Communion. The only thing to do is mention a forgotten mortal sin the next time you go to Confession. A forgotten venial sin doesn't need to be mentioned at all.

Was the forgotten sin forgiven?

Yes. The Catechism, quoting the Council of Trent, says that when you try to confess all the sins you can remember, you place all of them before God's mercy for pardon (CCC 1456). Not just the ones you managed to say. All of them.

Absolution doesn't depend on a perfect memory. It depends on an honest Confession: you examined your conscience reasonably, you were sorry, and you told the priest what came to mind. If a sin slipped away because you were nervous, rushed or simply human, God forgave it with the rest. You walked out of the confessional in a state of grace.

This happens to almost everyone. The line moves, your mind goes blank, and in the car you remember the thing you meant to say. It's a very common worry, and the answer is the same every time: you're forgiven, so mention it next time and keep going.

Do I have to confess it next time?

If it was a mortal sin, yes, at your next Confession. Church law asks you to confess every grave sin that hasn't yet been named in an individual Confession (Code of Canon Law, can. 988 §1). A forgotten sin was forgiven, but it was forgiven indirectly, along with the others. Naming it later brings it to the sacrament directly, the way Christ gave it to us.

There's no need to rush back tomorrow because of it. Mention it whenever you next go, in your usual rhythm. You could say:

• "In my last Confession I forgot to confess that I..."
• "There's a sin I forgot last time. I..."

Then carry on with your other sins as usual. The priest won't be surprised.

If it was a venial sin, you don't need to mention it. Venial sins don't have to be confessed at all, though you're welcome to. Our page on confessing venial sins explains why.

Do I need to go back to the same priest?

No. Any priest can hear it, in any parish. The forgotten sin simply joins your next Confession, wherever that is. You don't need to say which Confession you missed it in or explain how you forgot. Name the sin, and roughly how many times if it happened more than once, the way you would any other.

If the priest asks a question to understand it better, answer simply. Most of the time he'll just nod and let you continue.

Can I receive Communion before I confess it?

Yes. Because the sin was forgiven, you're in a state of grace and free to receive Communion. You don't need to go back to Confession first. The duty to name the sin later doesn't keep you from the altar now.

This is different from someone who knows they have an unconfessed mortal sin that was never brought to Confession at all. That person should go to Confession before receiving (CCC 1385). If you're not sure which applies to you, read Communion in mortal sin.

What if I remember while I'm still in the confessional?

Just say it. "Father, I forgot something" is fine at any point, even after he's given your penance, as long as he hasn't finished. If you remember right after you've stepped out and the line is short, you can also go back in. It isn't necessary, but some people find it gives them peace.

What if I left a sin out on purpose?

This is a different situation, and it's worth being honest and gentle with yourself about it. If you knowingly held back a mortal sin, out of shame or fear, the Confession wasn't valid. The Catechism puts it plainly: when someone knowingly withholds sins, nothing is placed before God's mercy, because a doctor can't heal a wound the patient is too ashamed to show (CCC 1456).

That sounds hard, but the way back is simple, and many people have walked it:

1. Go back to Confession. Any priest, any parish.
2. Tell him what happened. "Father, in my last Confession I held back a sin because I was ashamed." If you've been to Confession since, say how many times. Priests have heard this many times.
3. Confess the sin you held back, then repeat the other mortal sins from that Confession and from any Confessions since, because they weren't valid while the sin stayed hidden. If you received Communion during that time, say that too. The priest will help you sort it out. You don't have to work out the details alone.
4. Wait to receive Communion until then. Go to Mass in the meantime. Staying in the pew is common, and no one is keeping track.

The shame that made you hide the sin is usually far heavier than saying it. Once it's out, most people feel lighter than they have in years. If fear is what stops you, read scared of Confession.

Forgetting is not hiding

If you tend to worry, this part is for you. Leaving a sin out because your mind went blank, because you weren't sure it was serious, or because you couldn't find the words is not hiding it. Hiding means you remembered it clearly, knew it was a mortal sin, and chose not to say it.

If you can't tell which one happened, treat it as forgotten. Mention it next time and trust that the last Confession was good. Don't go back over old Confessions looking for sins you might have missed, and don't confess again sins that were already forgiven. If this kind of worry keeps returning, tell your confessor. It may be scrupulosity, and a steady priest can help you live in peace with it.

How to remember everything next time

You'll never remember perfectly, and that's fine. A few habits help:

• Examine your conscience before you go, not in line. A guide like our examination of conscience takes ten minutes.
• Write a short list. A few words for each sin, on paper or on your phone. Reading from it in the confessional is completely normal, and priests are used to it.
• Start with the hardest one. Say the sin you're most nervous about first, and the rest comes easier.
• Go more often. A month is much easier to remember than a whole year.

And if a sin comes back to you on the drive home next time, smile, make a note, and go about your day. You were forgiven before you even remembered it.