What is Treasury bills
In most countries you will find many types of government bonds. An important distinction is the duration of the bond, that is, the difference between the maturity date and the date when the bond was issued. For example, in the United States, government bonds maturing in one year or less are called Treasury bills.
Typically, bonds with a maturity of a year or shorter have no coupons. Instead, they are sold below the nominal amount at what is called the issue price. The issue price for a bond without coupons must be below the nominal amount. For example, if you pay 23,500 for a bond with a nominal amount of 25,000 maturing in one year, your interest rate is (25 000 -23 500)/23 500 = 6.38%.