If I link my credit card to my checking account to cover overdrafts, can the bank/credit union charge me a fee each time I use it to cover an overdraft?

In addition to the fee, the transaction will probably be considered a cash advance. This means you will be charged interest immediately on the amount charged to the credit card at the interest rate (or APR) for cash advances. This rate is usually higher than the interest rate for purchases. However, the total cost of paying an overdraft with your credit card is usually a lot less than the cost of paying an overdraft fee.