Demand Deposit securities are one-day certificates of indebtedness that are automatically rolled over each day until you request redemption.
(Equation 1)
Where:
I = Annualized effective Demand Deposit rate in decimals. If the rate is determined to be negative, such rate will be reset to zero.
P = Average auction price for the most recently auctioned 13-week Treasury bill, per hundred, to six decimals.
Y = 365 (if the year following issue date of the 13-week Treasury bill does not contain a leap year day) or 366 (if the year following issue date of the 13-week Treasury bill does contain a leap year day).
DTM = The number of days from date of issue to maturity for the most recently auctioned 13-week Treasury bill.
MTR = Estimated marginal tax rate, in decimals, of purchasers of tax-exempt bonds.
TAC = Treasury administrative costs, in decimals.
DDR = (1 + I)1/Y -1
(Equation 2)
31 C.F.R. §344.7