Definition: POS Fees are point-of-sale fees. Banks charge POS fees when you use your debit card in certain transactions. This would apply to transactions where you use your PIN number, or when you choose 'debit' on the retailer's payment machine. This does not apply to transactions where you sign for the purchase (like a credit card) or when you choose 'credit' on the retailer's payment machine.
Not all banks charge POS fees, so you should check the fine print at your bank. If your bank charges a POS fee, you should consider signing for purchases instead of using your PIN. However, you should be aware that somebody pays a fee for the transaction -- and it's probably you (whether you see it or not).
For details on the 'debit' vs 'credit' decision, see How Interchange Fees Work.
Alternate Spellings: P-O-S Fees, P.O.S Fees
Examples: My bank charges a $2 POS fee.
