In finance, bill has several meanings, depending on context. In one specific context, it refers to a treasury bill (T-bill): a type of treasury security that constitutes a short-term debt obligation in the form of a uniform security (fixed income security) issued and backed by a treasury department in a country. T-bills (treasury bills) have a a maturity of one year or less, i.e., usually for terms ranging from 4 to 52 weeks. Treasury bills (or simply, bills) are sold at a discount or at par (face value). Given their short-term life cycle, treasury securities are considered money market instruments.

In North American English, bill denotes a banknote or paper money- i.e., a printed form of currency that is issued by a central bank such as a dollar bill.

Bill may also denote the same meaning as a bill of exchange (finance bill).

In other contexts, bill refers to a printed or written statement of an amount of money owed for goods or services (bill could be for future payment in relation to sales on credit, or for immediate payment such as a restaurant bill) [synonym of invoice]. It is an itemized account of the cost of goods sold, services performed, or work done, arranged separately.

In financial law, a bill is a draft of a proposed law (draft law or proposed legislation) presented to parliament for discussion and possible enactment.