When you use your debit card as credit the only thing that happens differently is the way the transaction goes through.
When a debit card is run as credit card transaction the money takes a few days to come out of your bank account and with a debit card transaction the money comes out of your bank account right away.
So if you have a debit card and you don't have the money in the bank account and you run your debit card as debit then the transaction will be declined.
But if you run the debit card as credit then the transaction will go through usually and the money will be taken out of your bank account a few days later.
But if you have no money in your bank account to pay for the transaction then your bank account will be overdraft and you'll pay an overdraft fee.
When you make a purchase and select to process your payment as credit, it’s an offline transaction. “The funds for offline transactions are deducted after the merchant settles the purchase with the credit card processor and typically take 2-3 days to be reflected in your account balance.
When you use your debit card and your PIN (personal identification number), the transaction is completed in real time.
That’s also known as an online transaction and you authorize the purchase with your PIN, and the money is immediately transferred from your bank account to the merchant.
These are debit card transactions.