Amanda Bynes -- Living Off AmEx Gift Cards

Amanda Bynes is paying her bills off of American Express gift cards ... courtesy of her parents ... TMZ has learned.

Since Amanda's release from a psych hospital last week ... she's been roaming West Hollywood, eating out and going to hotels.

Our sources say Amanda's parents are giving her gift cards -- usually in the amount of $50. We're told on some days her parents will give her up to $100 if she needs the cash.

Amanda has no access to her money ... her parents have control under their temporary conservatorship. The money they're giving her is for living expenses.

The parents deliver the money to Amanda's court-appointed lawyer, who gives her the cards.