A prepaid debit card is different from a credit card, because you aren't borrowing money when you use it; instead you are spending money that you or someone else has loaded (or deposited) onto the card. These cards can be garnished by creditors, if they have the card's information.
Difficulty in Garnishing Prepaid Debit Cards
If a creditor cannot find an asset, it cannot have it garnished. Prepaid debit cards don't appear on your credit report, nor are they usually tied to your Social Security number. Since there are so many companies that issue the cards, it can be hard for a creditor to verify that an individual has a prepaid debit card, making it very difficult to garnish one.