To reinvest the funds from a maturing Treasury Note, Bond, or TIPS, or to reinvest the funds from a maturing Bill that has no scheduled repeat purchases, see "Learn more about Reinvesting Maturing Proceeds".
To reinvest in Treasury Bills with ease...use a repeat purchase schedule.
Select Zero-Percent C of I as the source of funds for future purchases.
Select Zero-Percent C of I as the maturity payment destination.