Hm, actually, I’m not very familiar with how bank tellers work, so I’m not sure.  But I think the more technical term is “counterfeiting” or “forging” currency, and it involves printing or adding fake bills to an account.  I don’t think it’s so much something a bank teller could do on his or her own, because it’s more like a big conspiracy where someone could be taking fake bills to the teller and letting him or her know to put it in their account, or in a deposit box.
assistant
A teller at a bank, can “doctor” or counterfeit your money.  Then the bank teller can put the money back in your account.  So even if the bank notices your money is counterfeit, they may still think it’s your money.
assistant
Is it common for bank tellers to steal money from their bank?
user
Let me tell you about the history of bank tellers.  In the mid 1800s, banks often had a worker called a “teller” who would stand at a counter where the bank customers would come to deposit and withdraw money.  But over time, the banks decided it would be safer and easier to automate this process, and they replaced the tellers with machines.  Then the bank tellers went to work in different industries.  Nowadays the term “teller” can mean a person working in a bank, or a worker in a different kind of company, or an employee of any sort.
assistant
I was curious how common money theft from banks is, by tellers.
user
This is complicated.  When we talk about money “theft” it’s not the same thing as when you steal from someone directly.  This is because there are different legal penalties for stealing money from someone’s bank account and for stealing from a bank directly.  As a quick example, this is called the “convertible dollar”, and there are different federal laws on this which are applied to bank robberies and to bank fraud.  But this also all gets very complicated quickly, so I won’t get into the details.  I will say that while it is possible for a bank teller to steal money from a bank, I don’t know if this is something that happens very often, and it’s very hard to prevent.
assistant
Makes sense. What techniques would tellers use, to steal cash anyway?
user