Could you please elaborate on what your ruling is based on?
As far as I know, technically it’s impossible to return the money. The company has to issue a receipt for every payment, and there’s a very orderly process. You can’t just go to the secretary and say, please take such-and-such amount of money that I received by mistake, and it would be a really bizarre story to tell her. I don’t want to return hours; I want to return money. For the simple reason that an hour out of the pathetic free time I have in the evening and on Friday with my family is worth more to me than the money valued according to regular hourly pay during work hours on workdays. I also want to use my vacation days as actual vacation. Right now I only want strict Jewish law, no extra piety and no discussion of what is morally proper in a general sense. Why can the company basically force me to pay with something equivalent to money, by means of which I would pay?
If, let’s say, I checked and really can’t return the money except informally by returning the hours—but I myself don’t want to repay the debt in hours, only in money—then in such a case can I get out of it? If someone I stole money from messes with me and wants me to repay him specifically in boxes of marshmallows, am I obligated to get him boxes of marshmallows? What am I supposed to do in that situation? I’ll note that my heart doesn’t exactly ache over this matter, and I have excuses and rationalizations till kingdom come, but nothing that could really stand up formally. So I’m asking only about binding Jewish law, no extras.
Maybe one more thing. It’s pretty clear to me that if I tell the whole story (say, to my manager), then he won’t tell me to pay anything. He’ll say it’s a shame and think somewhat negatively about me, but in my opinion he’ll almost certainly say, what happened happened, forget it and let’s not make calculations. In other words, I think I could get an official waiver of this debt—but the truth is that I price the need to admit it as a higher cost to me than the amount stolen, and I really don’t feel like doing it.
So my hair-splitting is this: formally, I think I’m the one who can choose how to return it. I choose to return it in money. They aren’t set up to receive money. So that’s their problem, and good health to them. The only thing they know how to take back is hours, and that I don’t want to give them. An official waiver I’m also not obligated to obtain. And maybe an unwitting waiver also counts as a waiver. Is this empty sophistry?

Maybe mark down a few days that you’ll work as vacation days?

Best regards, a giver of advice

You can ask them. But if they have no way to receive money, then you need to return the hours. If it’s inconvenient for you, you should have thought about that when you wasted the time.
In my opinion, you can’t return money to them. You owe them some number of work hours by virtue of a contract, and you didn’t provide them. Your contract with them is not void, since you continue to receive a salary there. So what exists here is a debt of work hours. If they can’t receive money, that’s because of laws that don’t depend on them. Either return the hours, or pay them money that also covers the associated costs.

All right, thank you very much. I’m not sure I understood all the reasoning (why exactly the debt is “work hours” and not money, and even if it is work hours then why, if the debt is work hours, I’m obligated to return hours rather than choose to return money, and what difference it makes whether there are laws or just company policy, and whether the laws depend on them or not), but if that’s what has to be done, then that’s what has to be done, and I’ll return the hours and that’s that.

Good luck, and in the place where penitents (with a commitment for the future) stand…