Suppose you put it in a high interest CD and just waited till the employer asked for the money back, then sold the CD and returned the money, keeping the earned interest?
OTOH, if the bank refuses to pay you what you’re owed, you can foreclose on them.
CDs have fixed terms, typically of 3 months or more. You are welcome to redeem the CD early, but if you do, you’ll only receive interest roughly equal to the current passbook savings rate.
Details vary all over the map from bank to bank but the basic idea is you can’t profitably buy a CD and redeem it early, thereby getting both (relatively) high interest and short term liquidity.
Yeah, if you break into a jewellery store without causing any damage, and take something, then just look at it for a while at home, then break back into the store and put it back, there was still an act of theft.
Your analogy fails on the “break into” part - the person in the OP was the legal owner of the bank account, they didn’t have to do anything illegal to access the money in it. If I order and pay for a $100 piece of jewelry, and the box I receive contains both what I ordered and a $1,000 piece of jewelry, is it theft to take the $1,000 piece of jewelry out of the box? To try it on? To wear it outside the house?
And furthermore re: the jewelry store analogy, when do you own the money in your account. That is the crux of the question. Do I own it as soon as it hits my account? Or is there a waiting time before I own it?
There’s a plot point along these lines in Sister Carrie: while locking up the office after hours, Hurstwood notices the safe door is open and decides to take out a few handfuls of cash, just for the thrill of holding that much money at once, with the full intent of putting it back. Unfortunately, he accidentally locks the safe while the money is still in his hands, and he doesn’t know the combination….
This is called “kiting,” and it’s a crime if you’re caught.
IANAL, but I believe that part of the crime includes “with the intent to deprive the owner”. In the billionaire case above, there was no intent (the extra funds were lost in the noise) and the money was repaid so there were no damages. The same would probably be true if you moved the money to a separate account with no co-mingling of funds, so it was clearly traceable and transparent and easily repaid. If you (a normal person with billions of dollars) withdraw the money in any way or spend it, I think you lose the ability to make that argument
ETA: Never mind, didn’t realize someone asked this already.
There is a a law called “theft of property lost by mistake”. It’s where someone intentionally uses property that they received by mistake rather than returning it. For instance, you’re at the pickup line at Best Buy to pick up a blender and they mistakenly put $10k of electronics in your trunk meant for another customer. You wouldn’t be entitled to use those electronics for your own use. You would need to make a reasonable effort to return the electronics. I would suspect that the person in the OP would be guilty of violating this kind of law. As soon as he noticed the error, he should have notified the bank or the customer. Intentionally taking the mistakenly deposited money out of the bank rather than notifying someone is where I would assume he became guilty of committing a crime.
Yeah, fair enough - some of that is just the inexact nature of analogies though.
Agreed. If his plan had worked - and it wouldn’t because even if he’d hit lucky at the casino on his first spin of the roulette wheel, he’d probably have carried on until he had made a loss - even if the plan had worked and he restored the account balance before anyone noticed, there would just have been a crime that was less easy to detect. When you commit a crime in the forest and there’s nobody there to hear it, it’s still a crime.
How exactly would you return the overpayment? What mechanisms do banks have if you know you got $1000 instead of $100? I suspect it would be to wait for the sender to try to correct the error on their end i.e. nothing you can do. What would your Payroll Department do if you showed up with $180,000 and say, “I think you overpaid me last week.”
I have no idea what the technically right answer is to this question, but this is IMHO. If this happened to me, I’d make it a priority to visit my bank and make sure there was a record of me saying that I suspected the transaction to be erroneous. That might not be the thing that restores things to where they should be, but it would establish my intent in the matter.
This part did actually happen to me once, a very long time ago, and not by anything like that amount. My pay packet contained way more money (cash in those days) than I was expecting to receive; there was a pay slip (handwritten in those days) that agreed with the amount in there, but no explanation of the anomalous amount. I was worried about it so I took it to the office and told them I thought I had been overpaid.
They didn’t know the reason either so my boss took the money into safekeeping, gave me a receipt and loaned me enough to get me through the weekend.
(It turned out not to be a mistake, but rather, a rebate - when I had started there they put me on the ‘emergency tax’ rate until my actual tax code was calculated - which was much lower than the emergency tax rate so I was owed back some of the withheld pay).
as others have noted, the offered hypothetical may or may not have technically been a crime depending on the jurisdiction, but, regardless of the jurisdiction, it would never ever get prosecuted if it was, since the original payer got their money back. It most likely would never even have been noticed.
Something like that actually happened to me once. My final paycheck from my college internship got direct deposited into my bank account twice, i.e. they accidentally gave me two paychecks. I sent an email to their HR person to inform them of the error, and their payroll provider did something to reverse the second transaction.
You don’t necessarily have to do the actual returning as in show up at the bank/payroll department with cash. The something you can do is notify them- at which point they can reverse the payment Anytime I’ve had a direct deposit , there’s always been some sort of notice that I’m giving them permission to clawback erroneous deposits.
You must have a rather… exclusive… circle of friends 
Sticking solely to the OP as presented, we get to dodge many of the hypotheticals - since he knew it was an overpayment, and knowingly and willfully used money he knew wasn’t his on a risky investment (the gambling, but would apply to any other thing, like crypto or stock speculation) he’s a criminal by intent though the exact legal definition may or may not be otherwise.