This is such a basic question, but I'm getting myself more confused. Reg E is applicable to deposit accounts not any type of credit accounts, right?

Right

Thanks

I guess I'm not done with my Reg E question. Notice of transfers varying in amount--(1) Notice. When a preauthorized electronic fund transfer from the consumer's account will vary in amount from the previous transfer under the same authorization or from the preauthorized amount, the designated payee or the financial institution shall send the consumer written notice of the amount and date of the transfer at least 10 days before the scheduled date of transfer.
How is the bank going to know 10 days prior to the transfer that it is going to differ and send notification? Example: my insurance comes out each month and if the amount changes I receive a notice from my insurance company NOT my bank. I need help sorting this requirement out please. Does the insurance company have a requirement to let me know 10 days in advance?

A more usable example might be the fact that your customers still receive their utility bills every month even though the funds are taken out of their account automatically. The utility company is the designated payee.

I have another example: I have a credit card with one bank and a deposit account at another bank. I set up my credit card monthly payment to be automatically debited from my deposit account. Who is responsible for Reg E? The credit card bank or my bank the holds my deposit account?

The credit card bank is responsible for obtaining a written authorization and for the contents of that authorization under Reg E §205.10 and for providing you with a copy of that authorization. It or your deposit-holding financial institution is responsible for complying with the notice of transfers in varying amounts requirements of §205.10(d). Typically, it would be the credit card bank that does it because it's in the best position to do so.

Your deposit-holding institution would be the one you'd go to if there were an error in one of the transfers, though.