A bill as a debt instrument has several meanings. It can be a negotiable debt obligation issued by the U.S. government and backed by its full faith and credit, having a maturity of one year or less. Exempt from state and local taxes, also called T-Bill or U.S. Treasury Bill or Treasury Bill. It may also be Paper currency or just an invoice of charges for products and services. For the emerging market it is any bill that can be traded.