They represent U.S. government obligations. The Treasury Department has weekly 3 month and 6 month T-Bill auctions. Once a month the Treasury Department auctions 6 month and 9 month T-Bills.

The Treasury Department also offers 'Tax Anticipation Bills' through special auctions. T-Bills are issued in denominations of $10,000 through $1,000,000. They have maturities of up to one year. There is an excellent secondary market for these. They are highly liquid. These are discounted in actual days based on a 360-day year.