U.S . Treasury Bills

Treasury Bills are direct obligations of the United Stated government. by law, they must have an original maturity of one year or less T-bills were first issued by the U.S. Treasury in 1929 in order to cover the federal government‘s frequent short-term cash deficits.
The federal government's fiscal year runs from October 1 to September 30. However, the largest single source of federal revenue, individual income taxes, is not fully collected until April of each year. Therefore, even in those rare years when a sizable federal budget surplus is expected, the government is likely to be sort of cash during the fall and winter months and often in the summer as well. During the spring, personal and corporate tax collections are usually at high levels, and the resulting inflow of funds can be used to retire some portion of those securities issued earlier in the fiscal year. T-bills are well suited to this seasonal ebb and flow of treasury cash since their maturities are short, they find a ready market among banks and other investors, and their prices adjust readily to changing market conditions.