Our Reg. E Opt-In processing is typically handled by one department within the bank, they review the account, change account coding, and mail out confirmation. It was just recently discovered during an audit that we had one isolated instance in which a customer service rep. changed the opt-in code on the account on the core to "account opted-In" back in December, but didn't bother to notify the department who normally handles this processing, and the CSR can't remember if he actually sent a consent form to customer back in Dec. (normally this is documented by thr dept who handles this processing). In a situation where we don't know whether confirmation was ever sent or not, seems we should send one now and follow-up with customer via a phone call. My question is, would we be expected to refund any OD fees incurred on account that were assessed on ATM and one-time POS transactions since December? Since technically we aren't suppose to assess these fees until after the confirmation has been mailed or delivered to the consumer?

I think you know the answer to your question. If you're in doubt, check out Official Interpretations to section 1005.17 of Reg E, in particular the last sentence of comment 17(b) - 7 (Confirmation) --- "An institution complies with the confirmation requirement if it has adopted reasonable procedures designed to ensure that overdraft fees are assessed only in connection with transactions paid after the confirmation has been mailed or delivered to the consumer."

If this is an isolated incident, I'd likely agree the bank is generally in compliance. But when you find an isolated incident like this one, you need to fix it. And that means getting the confirmation out and, from where I sit, a refund of any OD fees collected since the error. I hope there aren't many to refund.