counterfeit bill; counterfeit note
Refers specifically to fake paper money, such as counterfeit yen or dollar bills.
A counterfeit bill came out of the ATM.
forged document
Can refer to any forged paper document, but most commonly used for counterfeit money. The broader sense is less frequent.
The police seized counterfeit bills and forged documents.
Compound of 偽 (false, fake) and 札 (bill, tag, document). The reading ぎさつ uses the on'yomi of both characters.