Money is credited from unknown source

In a comment you clarified your question:

By legally binding I mean if I don't inform the bank on my own and spend the money instead the bank is able to prosecute me.

It likely depends on the type of transaction that caused the credit, among other factors. In most banking systems, there are a range of ways money can arrive in an account, and they have very different rules associated with them. Ultimately, it probably doesn't matter if you tell the bank or not - if the money is not supposed to be there, and it was deposited via a reversible method, all it takes is any other party involved to inform the bank and remove the money. Even that said, true errors do happen even with non-reversible transactions and banks may simply decide to error correct in that event.

Rather than worry about your liability for reporting the transaction, you should probably be more concerned that someone else will eventually discover the mistake and reverse the transaction. Ultimately, if you have no legitimate claim to the money, it's not yours, regardless of whether you tell anyone or not.

At the point when a record is credited with a mess of cash originating from an obscure source. Presently it doesn't really make a difference that the sum has originated from any specialized glitch, wrong exchange or unjustifiable methods. It doesn't have a place with you, Even in the event that you move it to another record you will be at risk to take care of it or deal with lawful indictments.

Accepting a sum doesn't make you a convict yet utilizing that cash for your own motivation is a wrongdoing without a doubt. On the off chance that you Google it you will without a doubt part of situations where individuals have dealt with indictments state it isn't right exchange or specialized glitch.