> Once a mistaken transaction showed up and disappeared a few hours later, with no trace left behind at all. I just assumed it was a mistake and didn't bother getting angry.
In many (all?) countries, your bank would've acted criminally. If money has been deposited to your account, only you or a court order can get it out again. If somebody "just does it", they are on a similar legal basis as somebody that forgot a jacket in your house and decides to break your lock and enter your house without your knowledge or authorization to get it back.
>A payor can attempt to reverse a payment made with an ACH credit only if the payor claims the beneficiary was already paid by a previous ACH credit entry, or the beneficiary was the wrong recipient of the funds, or the original ACH payment was in the wrong amount. Otherwise, the credit is considered final.
No clue how that works in different countries. Here it's pretty simple: once the money is in the account, you can't do anything. While the transaction isn't complete, you can cancel them obviously.
There's a good reason for that: nobody want's banks to take money out of accounts because they "feel that's the right thing to do".
There's one notable exception: SEPA direct debits getting reversed. Using DD requires a special agreement with your bank, however, and it won't happen that money ends up in your account without you requesting it - or if it does, you will get a phone call from your bank where somebody explains the situation, apologizes a dozen times and asks you to look into the matter and authorize a reversal. Acting on their own would be a criminal matter and likely be of interest to the regulators as well.
So if you decide not to reverse the mistake transaction you just get free money?
Unless it's a real lot of money going through the courts to get reimbursed would be impractical and if you transposed two numbers while typing an account number then you might not even know who the money went to.
> So if you decide not to reverse the mistake transaction you just get free money?
No, the law gets involved and at some point, a judge will decide whether you owe the sender the amount they mistakenly sent. It's basically the same for "I mistakenly sent you 100 that I meant to send to my friend" and "I mistakenly sent you 100 when I only meant to send you 50 that I owe".
And yeah, it's a hassle. At least you can generally find out which account the money went to, and with new IBANs, you need to mess up multiple digits, since they include a checksum. If the checksum doesn't match, the money bounces back into your account. Previously, some banks required that the account number and account holder match (within reasonable limits, misspelling the last name would work), but that changed with the IBAN system, only the account number matters now.
You're simplifying matters. If money was clearly sent in error, the bank can protect it from being spent (and subsequently refund it), unless the recipient disputes it:
> When you notify your bank or building society that you have made an electronic payment to the wrong account, your bank will commence action on your behalf within a maximum of two working days.
> Where your bank finds clear evidence of a genuine mistake, they will contact the receiving bank on your behalf with a request to prevent the money being mistakenly spent. As long as the recipient does not dispute your claim, you will subsequently receive a refund of the protected funds within 20 working days from when you notified your bank.
In many (all?) countries, your bank would've acted criminally. If money has been deposited to your account, only you or a court order can get it out again. If somebody "just does it", they are on a similar legal basis as somebody that forgot a jacket in your house and decides to break your lock and enter your house without your knowledge or authorization to get it back.