WASHINGTON (AP) — Congressional investigators say small fees add up for college students using college-issued debit and prepaid cards, which often are used to draw financial aid.

These types of cards are becoming more common on campuses.

The Government Accountability Office says the fees generally are similar to those other debit cards charge, and some students end up with out-of-network ATM fees. The agency says some cards have terms that charge a fee if students enter a pin number to receive money instead of signing to get cash back.

The agency says contract terms should be more transparent. Students are supposed to have convenient access to aid money. GAO asked the Education Department to define convenient access to ATMs and develop requirements that ensure students know their options. The department says it agrees.