From Motley Fool
For instance, Wells Fargo (NYSE: WFC) offers both types of overdraft protection. With a line of credit, you'll pay a fee based on the particular credit agreement you sign. On the other hand, if you link your checking account to a savings account, the fee is just $10. And if you have a brokerage account as a link, you may not have to pay any fees at all.
Similarly, Citigroup (NYSE: C) and its Citibank subsidiary charge just $5 for savings account transfers, compared to $30 for bounced checks. Bank of America (NYSE: BAC) charges $10 for an overdraft protection transfer, less than its $20 or $35 charges for bad checks.
Flagrant fees
However, overdraft protection isn't always a bargain. Some banks, knowing that overdraft protection saves customers from having to pay returned check fees to their merchants, charge the same amount to cover overdrafts that they charge for bounced checks. Customers often pay these charges gratefully, as it saves them the embarrassment of bouncing a check and prevents any damage to their credit ratings.