I'm looking for an opinion on whether or not we have to send adverse action notices out for the following situations. If a customer requests an action from us (such as closing a checking account) do we need to send an adverse action notice confirming that we took the action if there is a cooresponding overdraft line of credit with the account?

Also, should an adverse action notice be sent when we take a customer's request to lower a line of credit?

"Adverse Action" is translated as negative/denial action taken by the bank/creditor, not the customer, and includes the reasons the bank took action. Your scenarious do not apply. Check out REG B and FCRA for more concise guidance.