Evan,

Let's look at what the Catechism says about presumption:

It's classified as a sin against hope.

Presumption, then, is when you abuse God's mercy, relying on future forgiveness so you can get away with sinning now. To say in your heart, for example, that I can sin now and later go to Confession, so it's OK to sin, is the sin of presumption. The person who reasons,

"I can get drunk on Friday night because I can just go to Confession on Saturday."

is committing the sin of presumption; they are not really sorry for their sin, because they are not struggling to overcome it, they are abusing the sacrament. As the Catechism says, you're just assuming God will "forgive" you if you go through the motions without genuine conversion of heart and a will to turn away from sin.

Not everyone thinks this way when they commit a mortal sin, so not every mortal sin is automatically presumptuous.

• They may not be thinking of God when they commit the sin.
• Or the desire to commit the sin may outstrip their desire to please the Lord at that moment, but later they sincerely regret it.
• Or, they may be in the grips of a habitual or "besetting" sin or addiction — they realize it's wrong, they anticipate sincere repentance and reception of the Sacrament, but in the moment they are too overwhelmed or overpowered to avoid committing it.

Don't get wrapped around the axle thinking that just because you know something is a mortal sin beforehand, that it's automatically presumptuous. A question to ask yourself is:

• Do you sincerely want to overcome the sin and sincerely regret doing it when it happens?
• Are you trying to re-orient your will against committing the sin?
• Or are you "trying to get away with murder" and commit it with impunity, reasoning that the sacrament of Reconciliation will automatically make everything OK?
• Do you think you've got it made because hey, God will forgive me no matter what I do?

Imagine if you had a friend that always borrowed money from you. You always generously lent him the money and were patient about repayment. Suppose he thought,

"Hey, my friend will always lend and never confront me about repayment — what a deal, I can just keep borrowing money and this sap will keep giving it to me."

That's presumption. But suppose he struggled with his finances and never, despite his best efforts, could keep his head above water, and genuinely would repay you if he could, but somehow never is able. That's not presumption.

Simply realizing you'll have to go to Confession and knowing you're probably going to regret it later and repent and go to Confession doesn't necessarily make it presumptuous. However, what you describe:

"I will have to go to Confession, I don't care right now, but I will seek Confession."

could in fact be presumptuous thinking, so you're not off the hook. I think it may hinge on whether "but I will seek Confession" means,

• "God will forgive me so I can get away with this" or
• "I know based on past experience I will sincerely regret this, repent, and go to Confession, and part of me doesn't want to commit it, but in the moment, I can't deal with things."

What I recommend you do when you go to Confession is just bring this up with the priest. Say:

"I may have committed the sin of presumption in doing this, but I'm not sure. Can you help me examine my conscience and figure out whether I did or not?"

Hopefully, he'll be happy to work with you. If that doesn't work out, there is nothing wrong with saying,

"I suspect I committed the sin of presumption as well, because I reasoned <thus-and-so>, but I'm not 100% sure."

Then you are not lying.

Evan,

I should probably add that

• If, you definitively conclude that you are committing the sin of presumption, and
• If, you are entirely unwilling to give up the sin involved and work on overcoming it —

you should not go to Confession or receive the Eucharist until you are willing to do this.

Confession is for those who are repentant and contrite, i.e. those who do care about committing the sin, recognize the damage it does to their lives, and want to (even if only a little bit) turn away from it and receive healing. If you're steadfast in your sin and satisfied with committing it, don't bother; you're just incurring more wrath for yourself.

Evan,

I suspect you are being too scrupulous, but you need to discuss this with your Confessor in greater detail to verify and get more reliable counsel. We can give general advice, but for pastoral counsel you need a priest.

Find a confessor and stick with him every time you go to Confession.

Eric