The paying banker is responsible for honoring customer checks when sufficient funds are available. However, the banker must take precautions and ensure checks are valid before payment by verifying details like the form, date, amount, signatures, endorsements and for any alterations. The banker should also consider legal restrictions or orders to stop payment from the customer. Some key duties of the paying banker include verifying funds availability, checking for proper formatting of checks and adhering to the order of received checks when funds are insufficient.