I wonder if you'd be safe just sticking it in a savings account until they asked for it back. I mean, is it your responsibility to point out their mistake? And after how much time might they lose their right to demand it back?

The general consensus seems to be either leave it in the checking account until it is pulled back (and it almost always will be unless the amount is "small or reasonable" and therefor not caught in an audit) or directly contact the company immediately.

Moving it to a savings account is tricky because the automatic clawback will pull from whatever account it was sent into.

Once the company issues a W2 or 1099 the next year that covers it, I would consider it relatively safe to keep.

There's a third option for when the sum is really huge, like more money than you'll ever see in your life: find a good lawyer who can arrange transferring the money into some kind of trust fund, perhaps in a different country, that benefits your children, then wait for the knock on the door, expect to go to prison for a bit, but your children may be allowed to keep the money, and they might support you when you come out of jail. I think I read about a woman in New York successfully doing something like that with an accidental transfer from the United Nations, though I might be misremembering.

If it's a company or other body at that point you're trying to figure out what will let them settle their books - perhaps prison time for you will do so.

But other groups I'd be a bit more worried about them being willing to go to extra-judicial means to if not get the money back, at least get "revenge".

>Moving it to a savings account is tricky because the automatic clawback will pull from whatever account it was sent into.

As a non American this seems... Flawed.