Generally, you enter your PIN when you want cash back with your purchase.
Otherwise, you may run your transaction as credit unless your card is strictly an ATM/debit card.
Do you need to use a PIN for a debit card?
Card purchase PINs: You might also need a PIN to make purchases with your debit or credit card at a retailer. Again, the PIN proves that you are authorized to use the card. In the U.S., chip-enabled credit cards sometimes require a PIN at checkout, but a signature is more common.
Can a debit card be used without a PIN number?
Debit cards can be used without entering a personal identification number or PIN, in what is known as an “off-line” transaction. Unlike a credit card, however, if you lose your debit card, a thief can drain your entire bank account (and even your line of credit) — without knowing your PIN.
Do you need a PIN for credit or debit?
However, the store won’t incur the same hefty fee that they will have to pay if you choose credit, so stores like this option. A reader also asked a question about cash back. Only the debit/PIN# option allows this transaction, and as doing it this way avoids ATM fees, it’s a good choice when you do need some cash.
Do you have to sign when using a debit card?
The more expensive debit card is the one that requires a signature. Some retailers have decided to fight back against Visa by not allowing people to sign their signature or defaulting them to the PIN option. For now, if you use a debit card, opt for the one that requires your PIN.