I'm going to assume you are referring to periodic fees (often monthly or quarterly) charged against accounts that have reached the "dormant" status (however defined in your core system). Among my bank clients I see some charge the fee (often $3 or $5 a month/quarter) across the board, while others do not charge the dormant fee to accounts with at least a minimum balance (such as $100). In either case I always verify that their practice is properly disclosed at account opening. A fee structure such as this has always seemed to me to be at the discretion of the bank (and hopefully properly disclosed).
Now, if you are referring to a fee charged to an account prior to escheatment to the state I would expect that to be governed by state law. I do have a few bank clients that assess a fee (often $50, taken from the balance in the account) when escheating funds to the state. So, in Kentucky anyway, that is permissible.
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